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Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) Barium complex with 2,2,6,6-tetramethylheptane-3,5-dione and 4,7-diphenyl-1,10-phenanthroline Nataliya P. Kuz’mina,*a Irina E. Soboleva,a Valerii A. Ketskob and Sergei I. Troyanova a Department of Chemistry, M. V. Lomonosov Moscow State University, 119899 Moscow, Russian Federation. Fax:+7 095 939 0283 b N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 117907 Moscow, Russian Federation.Fax: +7 095 954 1279 The interaction between [Ba(dpm)]4 and anhydrous B-phen (mole ratio 1:2) in benzene leads to the formation of the new mixed-ligand complex Ba(dpm)2(B-phen)2·C6H6, which consists of the mononuclear molecules Ba(dpm)2(B-phen)2 with the cis arrangement of B-phen ligands involved in both intermolecular and intramolecular p–p interactions. In recent years, interest in the synthesis and crystal structure of volatile barium b-diketonates has been associated with their intensive use as volatile precursors in the metal-organic chemical vapour deposition (MOCVD) of barium-containing thin films.1 The use of barium b-diketonates as MOCVD precursors is complicated by low volatility and thermal stability of these complexes, which result from their oligomeric structure.2 For example, the well-known and widely used barium complex with 2,2,6,6-tetramethylheptane-3,5-dione (dipivaloylmethane, Hdpm) exhibits the tetranuclear structure [Ba(dpm)2]4,3 and its vapour consists of trinuclear and tetranuclear species.4,5 The interaction of [Ba(dpm)2]4 with neutral donor ligands Q (Lewis bases) leads to the formation of mononuclear mixed-ligand complexes [Ba(dpm)2(Q)n],2 where n = 1, Q = tetraglyme6 or n = 2, Q = 1,10-phenanthroline (phen).7 When heated, the [Ba(dpm)2(Q)n] complexes decompose with the elimination of more highly volatile Q ligands and with the formation of nonvolatile parent [Ba(dpm)2]4.It is rather difficult to synthesise a [Ba(dpm)2(Q)n] complex that can undergo sublimation without decomposition because of the low Lewis acidity of Ba(dpm)2.We suggested that the addition of a low-volatility ligand Q to [Ba(dpm)2]4 can result in higher thermal stability of [Ba(dpm)2(Q)n]. In this work, 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline, B-phen) is used as this neutral ligand Q, whose volatility is comparable to that of [Ba(dpm)2]4.Bathophenanthroline, as well as [Ba(dpm)2]4, evaporates in a temperature range of 220–240 °C at 0.1 Torr. Its complex with Ba(dpm)2 was synthesised and examined using different techniques including X-ray diffraction analysis. The interaction between [Ba(dpm)]4 and anhydrous B-phen (mole ratio 1:2) in benzene resulted in mixed-ligand complex Ba(dpm)2(B-phen)2·C6H6 1.† This procedure gave a white crystalline precipitate, which exhibited X-ray diffraction patterns consistent with those calculated for 1.The thermal analysis showed that C6H6 molecules were removed in the temperature range 50–100 °C to form Ba(dpm)2(B-phen)2, as was confirmed by elemental analysis.‡ † Synthesis of 1: Ba(dpm)2 (0.956 g, 0.19 mmol) and B-phen (1.262 g, 0.38 mmol) were suspended in benzene (30 ml), and the reaction mixture was heated at reflux with stirring until complete dissolution of the reactants.On cooling the solution, colourless prismatic crystals were formed; they were dried in a vacuum at room temperature (yield 80%). The solubility in C6H6 is 1.26 mmol dm–3. 1H NMR for BaC70H70N4O4 (25 °C, C6D6) d: 9.67 and 9.66 (4H), 7.52 (4H), 7.20 (20H), 7.16 and 7.13 (4H), 5.98 (2H), 1.41 (36H).IR spectra were measured on a UR-20 spectrometer. IR (Nujol and hexachlorobutadiene mulls, n/cm–1): 2855 and 2945 (C–H), 1560 and 1570 (C=O), 1530 (C=C), 850 (C–CMe3), 1265 (C–CMe3), 1650, 1655, 705, 740, 765, 790, 850, 940 and 980 (B-phen). Found (%): C, 73.40; H, 6.22; N, 4.44; Ba, 10.8.Calc. for BaC70H70N4O4·C6H6 (%): C, 73.25; H, 6.10; N, 4.50; Ba, 11.00. ‡ Found (%): C, 72.05; H, 6.14; N, 4.81; Ba, 11.8. Calc. for BaC70H70N4O4: C, 71.98; H, 6.00; N, 4.80; Ba, 11.74. Thermogravimetric analysis was performed on an OD-102 derivatograph in a nitrogen atmosphere at a heating rate of 5 K min–1. After the elimination of C6H6, three-step thermal decomposition took place in the temperature range 210–500 °C with the total weight loss 75%.An X-ray examination of 1 showed that it consists of the mononuclear molecules Ba(dpm)2(B-phen)2.§ The C6H6 molecules are situated in cavities and do not take part in coordination. The central Ba atom, lying on the twofold axis, coordinates four oxygen atoms of the two dpm ligands and four nitrogen atoms of the B-phen molecules [Figure 1(a)].All of the ligand donor atoms are involved in chelate rings. The coordination polyhedron of barium is a distorted tetragonal antiprism, as in the case of the known Ba(dpm)2(phen)2 complex.7 In 1, The Ba–O and Ba–N bond lengths [Ba–O(1) 2.683(5), Ba–O(2) 2.625(5), Ba–N(1) 2.969(5) and Ba–N(2) 2.986(5) Å] and the angles O(1)–Ba–O(2) and N(1)–Ba–N(2) [65.3(2) and 54.0(2)°, respectively] are close to the corresponding values in Ba(dpm)2(phen)2.7 The Ba(dpm)2(B-phen)2 and Ba(dpm)2(phen)2 molecules differ in the composition of neutral ligands.Bathophenanthroline is a phenanthroline derivative in which two H atoms are replaced by phenyl groups. This difference influences the mutual arrangement of ligands and the molecular packing mode in the crystal structure.The phen ligands in Ba(dpm)2(phen)2 are in the transposition and participate in intermolecular p–p interactions, forming infinite chains with a phen–phen distance of 3.46 Å.7 The characteristic feature of a Ba(dpm)2(B-phen)2 molecule is the cis-position of two B-phen ligands and the participation of their heterocyclic aromatic systems in both intermolecular and intramolecular p–p interactions [Figure 1(b)].The B-phen ligands from different molecules are stacked in parallel planes at a distance of 3.43–3.45 Å, forming chains aligned in the z direction. On heating in a vacuum, complex 1 eliminated a C6H6 molecule at a temperature lower than 75 °C. Within the temperature range 165–500 °C, the weight loss occurred in two steps.The first step (165–260 °C, a weight loss of 45%) corresponded to the evaporation of Ba(dpm)2(B-phen)2, as was confirmed by the elemental analysis and 1H NMR data obtained for the sublimate.¶ At the second step (260–500 °C), thermolysis of the organic moieties of the complex was observed. The total weight § Single-crystal X-ray diffraction analysis. A single crystal (0.2×0.2× ×0.3 mm) of 1 suitable for an X-ray diffraction examination was selected from the product obtained by slow crystallisation from a benzene solution of 1 in an evacuated ampoule.Crystal data for 1: C76H76N4O4Ba, M = 1246.75, orthorhombic, space group Pbcn, a = = 13.933(5) Å, b = 30.180(10) Å, c = 16.264(6) Å, V = 6868(6) Å3, Z = = 4, dcalc = 1.206 g cm–3, m = 6.28 cm–1.The data were collected on an Enraf-Nonius CAD 4 diffractometer (2 < q < 21.6°, monochromatic MoKa radiation, l = 0.7107Å, T = 293 K); 6322 unique reflections were measured, and 3453 reflections were used without absorption correction in calculations with the SHELX-97 program package. The structure was solved using a combination of direct and Fourier methods and refined by the full-matrix least-squares technique with the anisotropic thermal parameters for all non-hydrogen atoms.H atoms were placed in calculated positions. The final R values were R1 = 0.0569 and wR2 = 0.1267. Atomic coordinates, bond lengths, bond angles and thermal parameters have been deposited at the Cambridge Crystallographic Data Centre (CCDC). For details, see ‘Notice to Authors’, Mendeleev Commun., 1999, Issue 1.Any request to the CCDC should quote the full literature citation and the reference number 1135/47.Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) loss for 1 was 92%. The vacuum sublimation experiments corroborated that Ba(dpm)2(B-phen)2 evaporated congruently in the temperature range 200–250 °C; however, the evaporation was very slow.At temperatures higher than 250 °C, the complex underwent thermal decomposition. The behaviour of the Ba(dpm)2(phen)2 complex on heating was different from that of 1. The former was incongruently transformed into a vapour phase. Phenanthroline molecules were eliminated at 120–180 °C; next, the barium complex with dipivaloylmethane evaporated ¶ Thermogravimetric analysis was performed on a T-7000 Sinku-Riko thermal analyser in a vacuum (0.01 Torr) at a heating rate of 10 K min–1.Vacuum sublimation: samples of 1 were evaporated in glass tubes at a pressure of 0.01 Torr; the temperature range was 180–220 °C; the sample weight was 50 mg. The total weight loss of a sample was determined by gravimetry. All sublimate fractions collected in the course of isothermal heating within the range 200–245 °C exhibited spectrochemical and elemental analysis data that correspond to BaC70H70N4O4. at higher temperatures (180–220 °C).7 The difference between Ba(dpm)2(B-phen)2 and Ba(dpm)2(phen)2 in volatility can be explained by special features of the crystal structures.For 1, the enhanced thermal stability with respect to decomposition into B-phen and Ba(dpm)2 can be explained by the formation of a ‘superligand’ that consists of several B-phen ligands, which are strongly connected by intra- and intermolecular p–p interactions [Figure 1(b)].Thus, our approach to the synthesis of thermally stable Ba(dpm)2(Q)2 compounds using low-volatility neutral ligands was successful. Compound 1 is the first example of a Ba(dpm)2(Q)2 complex that undergoes congruent evaporation; however, unfortunately, the volatility of this compound was found to be rather low.This work was supported by the Russian Foundation for Basic Research (grant no. 96-03-32937a). References 1 M. Tiita and L. Niinisto, Chemical Vapour Deposition, 1997, 3, 167. 2 A. Drozdov and S. I. Troyanov, Main Group Metal Chemistry, 1996, 547. 3 A. Drozdov and S. I. Troyanov, Polyhedron, 1992, 3, 2877. 4 A. S. Alikhanyan, I. P. Malkerova, N. P. Kuz’mina, V. K. Ivanov and A. R. Kaul’, Zh. Neorg. Khim., 1994, 39, 1534 (Russ. J. Inorg. Chem., 1994, 39, 1465). 5 N. I. Giricheva, N. A. Isakova, N. P. Kuz’mina, G. V. Girichev, V. M. Petrov and A. R. Kaul’, Zh. Neorg. Khim., 1996, 41, 1523 (Russ. J. Inorg. Chem., 1996, 41, 1457). 6 R. G. Gardiner, D. W. Brown, P. S. Kirlin and A. L. Rheingold., Chem. Mater., 1991, 3, 1053. 7 N. Kuzmina, V. Ivanov, S. I. Troyanov and L. Martynenko, J. Chem. Vap. Deposition, 1994, 3, 32. Figure 1 (a) Molecular structure of Ba(dpm)2(B-phen)2 and (b) a fragment of the molecular packing in the crystal structure. O(2A) Ba N(2) O(2) O(1) N(2A) N(1) N(1A) 0 x z O(1A) (a) (b) Received: 21st January 1999; Com. 99/1429

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Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) Characterization of structures and spectra of holmium complexes formed in the CO and N2 matrices Aleksandr Yu. Ermilov, Aleksandr V. Nemukhin* and Vasilii M. Kovba Department of Chemistry, M. V. Lomonosov Moscow State University, 119899 Moscow, Russian Federation. Fax: +7 095 932 8846 The equilibrium geometry configurations and high-frequency IR spectra for the complexes HoLn (L = CO, N2, n = 1–6) are characterised by ab initio quantum-chemical calculations.Matrix isolation studies provide a large body of data on the structures of d-metal compounds.1,2 However, only few attempts have been performed to obtain and characterise lanthanide compounds in matrices. Direct co-condensation of metal atoms with ligands, combined with matrix isolation techniques and spectroscopic detection, offers a promising route to novel model complexes of lanthanides.Recently, experimental data on the samarium and holmium systems have been reported,3,4 which were supported by the ab initio quantum-chemical simulation.5 In this work we present the first data on holmium complexes that can be formed in cryogenic molecular matrices of CO and N2.Experiments with the deposition of holmium atoms in both of the matrices, controlled by UV-VIS spectroscopy, demonstrated that sharp atomic absorption bands considerably decreased after irradiation for a short time. This fact suggests that new substances were formed. These new compounds were characterised by the IR spectral bands at 1981 cm–1 in case of CO matrices and 2110/2097 cm–1 in case of N2 matrices.This evidences that, most likely, the complexes HoLn (L = CO, N2) have been synthesised; however no detailed conclusions can be drawn from the experimental data. Although it is difficult to apply quantum-chemical methods to direct calculations of the structures and spectra of lanthanide compounds,6,7 the information gained by this modeling is of importance for the qualitative interpretation of experimental data.Since our goal is to evaluate the low-resolution vibrational spectra of conceivable complexes and to suggest molecular models consistent with the experimental observations, we report here the results of ab initio quantum-chemical calculations which do not pretend for high accuracy with respect to other properties.It is well known that the treatment of the transition metal carbonyl complexes in terms of quantum chemistry is very difficult.8 However, the literature data9 indicate that simple self-consistent field (SCF) calculations even with the small basis sets 3-21G result in reasonable predictions for the structures and high-frequency vibrational bands.A successful description of structures of lanthanide complexes at a relatively low quantum-chemical level10 also provides support to the use of approaches that take no account of electron correlation effects and sophisticated basis sets. The key problem in the modelling of properties of heavy elements using quantum-chemical approaches is the use of effective core potentials (or pseudopotentials) which permit one to consider explicitly only the valence shells of electrons.The main reason is the desire not only to simplify the treatment but also to present a route to incorporate relativistic effects through the parameters of the corresponding pseudopotentials. In this work we used the pseudopotential developed by Cundari and Stevens11 for holmium, which considers the f-shell electrons along with (5s, 5p and 6s) as valence ones.Attached to this pseudopotential, the basis set [4s4p2d2f] is employed for Ho along with the conventional 3-21G basis for C, O and N. The calculations were performed using the GAMESS program package.12 Within the selected options, the complete geometry optimization can be routinely carried out followed by the harmonic vibrational analysis for the species HoLn (L = CO, N2, n = 1–6).To provide additional support to the calculation procedure, we have computed the equilibrium geometry configurations and harmonic frequencies for the well-characterised transition metal hexacarbonyls Cr(CO)6 and W(CO)6. The metal atoms are described by the pseudopotential parameters of Stevens et al.13 (i.e.adjusted following exactly the same principles as for Ho) and the light atoms, by the 3-21G basis set, and the properties are evaluated within the SCF approximation. The bond lengths calculated for both of the systems [RCrC = 1.999 Å, RCO = 1.136 Å Table 1 Calculated geometry parameters and the highest (unscaled and scaled with the factor 0.91) vibrational frequencies for the Ho(CO)n species.For n = 3, no stable minimum energy structures have been found. Species Symmetry RHoC/Å RCO/Å Unscaled frequencies/ cm–1 (IR intensities/ D2 Å–2) Scaled IR-active frequencies/ cm–1 HoCO C•h 2.19 1.17 1965 (39) 1788 Ho(CO)2 D•h 2.35 1.14 1967 (359) 2201 1790 Ho(CO)4 C4v 2.47 1.14 2100 (81) 2184 2280 1911 Ho(CO)5 C4v 2.30 2.44 1.14 1.15 2038 (58) 2174 2188 (59) 2287 1855 1991 Ho(CO)6 D2d 2.41 2.47 1.15 1.13 1926 1994 (209) 2181 (109) 2190 2306 1814 1984 Table 2 Calculated geometry parameters and the highest (unscaled and scaled with the factor 0.91) vibrational frequencies for the Ho(N2)n species. The minimum energy structure for n = 1 corresponds to the HoN + N composition. Species Symmetry RHoN/Å RNN/Å Unscaled frequencies/ cm–1 (IR intensities/ D2 Å–2) Scaled IR-active frequencies/ cm–1 HoN···N C•h 1.91 Ho(N2)2 D•h 2.28 1.10 2117 (301) 2285 1927 Ho(N2)3 D3h 2.28 1.12 2155 2967 (293) 2700 Ho(N2)4 C4v 2.41 1.09 2309 (92) 2336 2445 2104 Ho(N2)5 C4v 2.24 2.37 1.11 1.10 2043 (126) 2271 (186) 2354 2426 1860 2066 Ho(N2)6 D4h 2.35 2.38 1.1098 1.1096 2248 (190) 2294 2297 (153) 2302 2449 2045 2090Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) for Cr(CO)6 and RWC = 2.074 Å, RCO = 1.139 Å for W(CO)6] agree, within the expected limits, with the experimental estimates14 [RCrC = 1.914 Å, RCO = 1.140 Å for Cr(CO)6 and RWC = 2.058Å, RCO = 1.141 Å for W(CO)6]. In both cases the computed highest harmonic vibrational frequencies [2305, 2219 and 2212 cm–1 for Cr(CO)6 and 2309, 2219 and 2184 cm–1 for W(CO)6] can be brought to a precise agreement with the experimental data confirmed by the high-level ab initio calculations14,15 by using a customary scaling procedure with the scaling factor 0.91 conventional for the SCF treatment. Therefore, this particular scaling factor (0.91) is used in this work to correct the computed vibrational frequencies of HoLn in the 2000 cm–1 region.For all of the species HoLn (L = CO, N2, n = 1–6), the quartet spin multiplicity was assumed in accordance with the known ground state term of the Ho atom.16 An additional examination of effective electronic configurations was carried out using the natural population analysis by Weinhold et al.17 According to this analysis, the natural electron configuration of holmium atoms in these complexes can be described as the intermediate between the cases …4f 106s15d1 and …4f 105d1 with the formal charge at the atom between +1 and +2.A comparison of the data on the hexaligand species is most interesting. The configuration for Ho(CO)6 can be described as …4f 106s0.45d0.8 with the natural charge at Ho +1.77, and for Ho(N2)6 the electronic configuration is …4f 106s0.255d1.16 with the charge at Ho +1.57.Tables 1 and 2 show the calculation results. Note that several other stationary points (saddle points) with imaginary frequencies were detected on the potential energy surfaces. Higher energy isomers were also found [e.g., the D3h structure for Ho(N2)5]. Tables 1 and 2 summarise only the data on the lowest energy stable isomers. If we compare the predicted positions of IR-active bands after the scaling (Tables 1 and 2) with those observed experimentally in the matrix studies (1981 cm–1 in case of CO matrices and 2110/2097 cm–1 in case of N2 matrices), the majority of conceivable products Ho(CO)n and Ho(N2)n should be rejected.Among the carbonyls, the best candidate Ho(CO)6 (theoretical band at 1984 cm–1) perfectly matches the experimental observations. The Ho(CO)5 species with the theoretical band at 1991 cm–1 may also be taken into consideration.Of the dinitrogen complexes, Ho(N2)6 with the theoretical band at 2090 cm–1 seems to be the best candidate; however, unlike the carbonyl complexes, the Ho(N2)4 species with the band at 2101 cm–1 may be considered. The predicted geometry configurations of the complexes Ho(CO)6 and Ho(N2)6 are illustrated in Figure 1.According to the results of our vibrational analysis, these structures are most likely formed upon deposition of holmium atoms into the corresponding matrices. Interestingly, there is a slight distinction between the structures depending on the ligand, namely, the D2d symmetry for Ho(CO)6, but D4h for Ho(N2)6.The above differences in the effective electronic configurations of Ho, in particular, different occupations of the 5d orbital (0.8 for CO and 1.16 for N2), as well as different natural charges, may account for such a distinction. The formation of Ho(CO)5 and Ho(N2)4 species cannot also be excluded. We thank Dr. W. E. Klotzbücher (Max-Planck-Institut für Strahlenchemie) for providing the results of his experimental studies, valuable discussions and suggestions.This work was supported in parts by the Russian Foundation for Basic Research (grant no. 98-03-33168). A. Yu. Ermilov acknowledges the INTAS programme for the support of young scientists. References 1 M.D.Morse, Chem. Rev., 1986, 86, 1049. 2 M. J. Almond and A. J. Downs, Adv. Spectrosc., 1989, 17, 1. 3 W. E. Klotzbücher, M. A. Petrukhina and G. B. Sergeev, Mendeleev Commun., 1994, 5. 4 W. E. Klotzbücher, M. A. Petrukhina and G. B. Sergeev, J. Phys. Chem. A, 1997, 101, 4548. 5 A. V. Nemukhin, A. Yu. Ermilov, M. A. Petrukhina, W. E. Klotzbücher and J. Smets, Spectrochim. Acta, 1977, A53, 1803. 6 P. Pyykko, Chem. Rev., 1988, 88, 563. 7 M. Dolg and H. Stoll, in Handbook on the Physics and Chemistry of Rare Earths, eds.K. A. Gschneider and L. Eyring, Elsevier, Amsterdam, 1996, vol. 22, ch. 152. 8 E. R. Davidson, K. L. Kunze, F. B. C. Machado and S. J. Chakravorthy, Acc. Chem. Res., 1993, 26, 628. 9 A. W. Ehlers and G. Frenking, J. Am. Chem. Soc., 1994, 116, 1514. 10 T. R. Cundari and L. C. Saunders, J. Chem. Inf. Comput. Sci., 1998, 38, 523. 11 T. R. Cundari and W. J. Stevens, J. Chem. Phys., 1993, 98, 5555. 12 M. W. Schmidt, K. K. Baldridge, J. A. Boatz, S. T. Elbert, M. S. Gordon, J. H. Jensen, S. Koseki, N. Matsunaga, K. A. Nguyen, S. J. Su, T. L. Windus, M. Dupuis and J. A. Montgomery, J. Comput. Chem., 1993, 14, 1347. 13 W. J. Stevens, M. Krauss, H. Basch and P. G. Jasien, Can. J. Chem., 1992, 70, 612. 14 A. W. Ehlers, Y. Ruiz-Morales, E. J. Baerends and T. Ziegler, Inorg. Chem., 1997, 36, 5031. 15 A. Berces and T. Ziegler, J. Phys. Chem., 1994, 98, 13233. 16 A. A. Radzig and B. M. Smirnov, Spravochnik po atomnoi i molekulyarnoi fizike (Handbook on atomic and molecular physics), Atomizdat, Moscow, 1980 (in Russian). 17 A. E. Reed, R. B. Weinstock and F. Weinhold, J. Chem. Phys., 1985, 83, 735. 2.41 2.47 2.35 2.38 Figure 1 Geometry configurations of Ho(CO)6 (left) and Ho(N2)6 (right). Received: 22nd December 1998; Com. 98/1417

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年代:1999

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Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) Synthesis and characterization of conformationally flexible phosphonated cyclophanes Giuseppe A. Consiglio,a Salvatore Faillab and Paolo Finocchiaro*a a Istituto Chimico, Facoltà di Ingegneria, Università di Catania, 95125 Catania, Italy. Fax: +39 095 738 2798; e-mail: pfinocchiaro@ic.ing.unict.it b Dipartimento di Ingegneria Chimica, dei Materiali delle Materie Prime e Metallurgiche, Università di Roma ‘La Sapienza’, 00161 Rome, Italy The phosphorylated calix[4]arenoid para- and meta-substituted cyclophane tetramers, which were synthesised in good yields starting from parent cyclic hydrocarbons, show a ‘saddle-shaped’ rigid conformation in solution, and the methylenephosphonic acid dialkyl ester groups are in a strategic position for complexation with neutral guests.Conformationally flexible medium-sized cyclophanes are macrocycles of great importance for supramolecular chemistry and thus the attention of chemists has been focused on a synthetic route towards such molecules.1–3 In particular, great interest was created in the synthesis and characterization of constrained macrocycles for the use as specific receptors for the selective complexation of neutral guests3–5 with the emphasis on the binding of a wide variety of biologically relevant molecules.Moreover, chemically robust aromatic macrocycles able to complex cations, in particular, lanthanides, are needed as luminescent sensors and for diagnostic bioassay6,7 in medicine. Previously, we have performed the synthesis of tetrameric aryl macrocycles connected by methylene bridges and prepared spirobiindane bis(phosphonate)8 unit 1.We decided on the use of this synthon for preparing macrocycles that possess ancillary groups such as phosphonic ones in order to produce suitable hosts for a wide variety of neutral guests and for transition elements. It has been shown previously9 that crystalline, high-melting tetrameric methaparacyclophane 2 possesing two mesitylene and two durene units connected by methylene bridges can be easily synthesised by Friedel–Crafts procedures.Chloromethylation10 of 2 yielded 3, which gave phosphorylated calix[4]arenoid tetramers 4a–c by the Arbuzov reaction using trialkyl phosphites (Scheme 1).† We found by NMR investigations at room temperatures that macrocycles 4a–c show restricted rotation of the durene rings as evidenced by the presence of two sharp singlets for the durene methyl groups at d 1.43 and 2.34 ppm in the ratio 1:1.Furthermore, these data reveal that one set of signals is strongly upfield shifted by the aromatic ring current effect. Analogous shielding is evidenced by the mesitylene methyl groups posi- Cl Cl EtNO2 SnCl4 2 CS2/SnCl4 ClCH2OMe 3 CH2Cl CH2Cl P(OR)3 reflux 4 CH2 CH2 P O OR OR P O OR OR 4a R = Me 4b R = Et 4c R = Pri Scheme 1 HO OH (EtO)2(O)PO OP(O)(OEt)2 CCl4/HP(O)(OEt)2 NEt3 THF/LDA –78 ºC HO OH P P O OEt OEt EtO O EtO 1 O O O O O O P P O O O O O O 1 + Pentaethylene glycol ditosylate MeCN/CsF reflux 5 Scheme 2Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) tioned inside the methylene bridging groups which resonate at d 0.87 ppm, i.e., ca. 1.46 ppm upfield compared to the relevant methyl groups in the linear parent subunit model 2,4,6-trimethylbenzylphosphonic acid dialkyl ester. These data are consitent with the conformation of macrocycles 4a–c in solution as an 1,3-alternated saddle-shaped geometry in which two durene units are perpendicular to the plane identified by the four bridging methylene groups, whereas the mesityl rings are alternatively up and down with their inner methyl groups pointing inward the aromatic ring current of the durene rings.Thus, the methylenephosphonic groups are also alternatively up and down of the cage in strategic positions for complexing with neutral guests.Due to the skeleton symmetry, the bridging methylene protons appear as two doublets at ca. 4.08 ppm; the methylene groups attached to the phosphonic groups appear as a sharp doublet due to the coupling with phosphorus (2JHP 21.5 Hz), whereas the methyls or methylenes of alkyl groups R in the –P(O)(OR)2 moiety, due to the tetrahedral geometry of the phosphorus, reside in a diastereotopic environment when R is Pri or Et, whereas they are enantiotopic for R = Me.It follows that the –P(O)(OMe)2 protons in 4a appear as a sharp doublet due to the coupling with phosphorus (3JHP 10.5 Hz); the methyl protons of the ethoxy groups in 4b appear as a triplet, whereas the methylene protons manifest themselves as two distinct multiplets, (AB systems coupled with phosphorus); and the methyl protons of the isopropyl groups in 4c appear as two doublets (Dn 0.10 ppm, 2JHH 6 Hz).By condensing spirobiindane monomer 1 with pentaethylene glycol ditosylate under conditions of high dilution, macrocycle 5 was synthesised in good yield (> 40%, Scheme 2).‡ The NMR investigations of host 5 at room temperature showed that it possesses a C2 symmetry in solution and the sets of signals due to the methylenes of the crown and the spirobiindane moiety are in the expected range.† General procedure for the synthesis of phosphorylated methaparacyclophanes 4a–c. To 2 mmol (1.45 g) of chloromethyl methaparacyclophane derivative 2 was added, under a nitrogen atmosphere, 50 ml of trialkylphosphite. The reaction mixture was refluxed for 6 h, until no more unreacted starting material was observed by TLC.After evaporation of the solvent, the residue was refluxed with cyclohexane, then cooled, filtered and dried to give the diphosphonate derivative as a white powder, which was crystallised from dichloromethane–cyclohexane. 4,18-Bis(dimethoxyphosphorylmethyl)-3,5,7,10,11,13,14,17,19,21,24, 25,27,28-tetradecamethyl[1.1.1.1]methaparacyclophane 4a, (1.32 g, 83%), mp > 300 °C. 1H NMR (CDCl3) d: 0.87 (s, 6H, int ArMe), 1.43 (s, 12H, int DureneMe), 2.34 (s, 12H, ext DureneMe), 2.51 (s, 12H, ext ArMe), 3.45 (d, 4H, CH2P, 2JHP 21.5 Hz), 3.66 (d, OMe, 3JHP 11 Hz), 4.08 (dd, 8H, ArCH2, JHH 15.5 Hz). 13C NMR, d: 16.56, 17.43, 17.82, 18.85, 29.05 (d, 1JCP 137.4 Hz), 30.03, 52.67, 125.5 (d, JCP 10 Hz), 131.67, 132.8 (d, JCP 6 Hz), 135.31 (d, JCP 3.7 Hz), 136.96, 139.36 (d, JCP 3.7 Hz). 31P NMR d: 30.88. CI-MS (NH3) m/z: 801 (8%, M+), 819 (100%, [M + NH4]+). 4,18-Bis(diethoxyphosphorylmethyl)-3,5,7,10,11,13,14,17,19,21,24, 25,27,28-tetradecamethyl[1.1.1.1]methaparacyclophane 4b: (1.37 g, 80%), mp 206–208 °C. 1H NMR (CDCl3) d: 0.87 (s, 6H, int ArMe), 1.28 (t, 12H, OCH2Me, JHH 7 Hz), 1.43 (s, 12H, int DureneMe), 2.34 (s, 12H, ext DureneMe), 2.51 (s, 12H, ext ArMe), 3.43 (d, 4H, CH2P, 2JHP 22 Hz), 4.04 (m, 16H, ArCH2 + OCH2Me). 13C NMR, d: 16.56, 17.43, 17.82, 18.85, 29.05 (d, 1JCP 137.4 Hz), 30.03, 52.67, 125.5 (d, JCP 10 Hz), 131.67, 132.8 (d, JCP 6 Hz), 135.31 (d, JCP 3.7 Hz), 136.96, 139.36 (d, JCP 3.7 Hz). 31P NMR, d: 30.88. CI-MS (NH3) m/z: 857 (10%, M+), 875 (100%, [M + NH4]+). 4,18-Bis(diisopropyloxyphosphorylmethyl)-3,5,7,10,11,13,14,17,19,21, 24,25,27,28-tetradecamethyl[1.1.1.1]methaparacyclophane 4c, (1.46 g, 80%), mp 250–252 °C. 1H NMR (CDCl3) d: 0.86 (s, 6H, int ArMe), 1.22 (d, 12H, OCHMe, JHH 6.5 Hz), 1.31 (d, 12H, OCHMe, JHH 6 Hz), 1.44 (s, 12H, int DureneMe), 2.34 (s, 12H, ext DureneMe), 2.51 (s, 12H, ext ArMe), 3.36 (d, 4H, CH2P, 2JHP 21.5 Hz), 4.06 (dd, 8H, ArCH2, JHH 15 Hz), 4.66 (m, 2H, OCH). 13C NMR, d: 16.65, 17.38, 18.00, 18.77, 23.89, 24.08, 30.79 (d, 1JCP 139.8 Hz), 32.97, 126.4 (d, JCP 9 Hz), 131.51, 132.78 (d, JCP 6 Hz), 134.8 (d, JCP 3.5 Hz), 136.98, 139.05 (d, JCP 3.5 Hz). 31P NMR, d: 26.85. CI-MS (NH3) m/z: 913 (15%, M+), 931 (100%, [M + NH4]+). Macrocycle 5 is a novel chiral crown ether possessing phosphonate moieties in strategic positions, which may enhance the possibility of hydrogen bonding in three-dimensional chiral recognition.The authors gratefully acknowledge financial support of this work by C.N.R. and MURST. References 1 (a) Topics in Current Chemistry, Cyclophanes I, ed. F. Vögtle, Springer, Berlin, 1983, vol. 113; (b) Topics in Current Chemistry, Cyclophanes II, ed.F. Vögtle, Springer, Berlin, 1983, vol. 115; (c) F. Vögtle, Cyclo-phanes Chemistry, Wiley, Chichester, 1993. 2 F.Diederich, Monographs in Supramolecular Chemistry. Cyclophanes, ed. J. F. Stoddart, The Royal Society of Chemistry, London, 1991. 3 Comprehensive Supramolecular Chemistry, eds. D. D. MacNicol, F. Toda and R. Bishop, Pergamon, Oxford, 1996, vol. 6. 4 (a) J.-M. Lehn, Angew.Chem., 1988, 100, 91; (b) D. J. Cram, Angew. Chem., 1988, 100, 1041; (c) F. Diederich, Angew. Chem., 1988, 100, 372; (d) A. Collet, Tetrahedron, 1987, 43, 5725; (e) K. Koga and K. Odashima, J. Inclusion Phenom. Mol. Recognit. Chem., 1989, 7, 53; (f) D. N. Reinhoudt and H. den Hertorg, Jr., J. Bull. Soc. Chim. Belg., 1988, 97, 645; (g) D. N. Reinhoudt and P. J. Dijkstra, Pure Appl.Chem., 1988, 60, 477. 5 (a) E. Weber, Progress in Macrocyclic Chemistry. Synthesis of Macrocycles, the Design of Selective Complexing Agents, eds. R. M. Izatt and J. J. Christensen, Wiley & Sons, New York, 1989, vol. 3, pp. 337; (b) A. D. Hamilton, A. Muehldorf, S.-K. Chang, N. Pant, S. Goswami and D. van Engen, J. Inclusion Phenom. Mol. Recognit. Chem., 1989, 7, 27; (c) J.Rebek, Jr., Angew. Chem., Int. Ed. Engl., 1990, 29, 245; (d) S. C. Zimmerman and W. Wu, J. Am. Chem. Soc., 1989, 111, 8054. 6 S. W. A. Bligh, N. Choi, D. S. T. C. Green, H. R. Hundson, C. M. McGrath and M. McPartlin, Polyhedron, 1993, 12, 2887 and references therein. 7 S. Aime, A. S. Batsanov, M. Botta, R. S. Dickins, S. Faulkner, C. E. Foster, A. Harrison, J. A. K. Howard, J.M. Moloney, T. J. Norman, D. Parker, L. Royle and J. A. G. Williams, J. Chem. Soc., Dalton Trans., 1997, 3623. 8 G. A. Consiglio, S. Failla, P. Finocchiaro and V. Siracusa, Phosphorus, Sulfur and Silicon, 1998, 134/135, 413. 9 F. Bottino, G. Montaudo and P. Maravigna, Ann. Chim. (Rome), 1967, 57, 972. 10 S. Pappalardo, G. Ferguson and J. F. Gallagher, J. Org. Chem., 1992, 57, 7102.‡ 6,6'-Bis(diethoxyphosphoryl)-7,7'-spirobiindano-23-crown-6 5. Solutions of 1 (0.58 g, 1 mmol) and pentaethylene glycol ditosylate (1 mmol) in freshly distilled MeCN (200 ml in total) were added dropwise, at equal rates over a period of 6 h from two different dropping funnels, to a stirred suspension of anhydrous CsF (0.91 g, 6 mmol) in anhydrous MeCN (400 ml) at a refluxing temperature for 48 h; next, the solvent was evaporated to give a white powder, which was collected with diethyl ether by filtration and washed several times with water.The product was purified by crystallisation from cyclohexane–ethyl acetate to give crown compound 5 (0.32 g, 40%), mp 148–150 °C. 1H NMR (CDCl3) d: 1.34 (s, 6H), 1.35 (t, 6H, OCH2Me, JHH 7 Hz), 1.37 (m, 12H), 2.11 (d, 2H, JHH 13 Hz), 2.37 (d, 2H, JHH 13 Hz), 3.59 (m, 12H), 3.61 (m, 2H), 3.77 (m, 2H), 3.83 (m, 2H), 3.99 (m, 2H), 4.2 (m, 10H), 6.34 (d, 2H, 4JHP 6.5 Hz), 7.64 (d, 2H, 3JHP 15 Hz). 13C NMR, d: 16.45 (d, JCP 6.4 Hz), 30.30, 31.37, 43.15, 62.05 (m), 68.64, 69.11, 70.29, 70.51, 70.63, 107.81 (d, JCP 10.6 Hz), 116.14 (d, 1JCP 187.3 Hz), 128.77 (d, JCP 7.6 Hz), 144.6 (d, JCP 14.4 Hz), 156.42 (d, JCP 2 Hz), 160.51 (d, JCP 3.5 Hz), 31P NMR, d: 18.34. FAB-MS, m/z: 784 (100%, [M + H]+). Received: 4th February 1999; Com. 99/1437

ISSN:0959-9436     

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) Stable free imino and nitronyl nitroxyl radicals of the acetylene series: synthesis, electronic absorption spectra and magnetic resonance parameters Eugene V. Tretyakov, Rimma I. Samoilova, Yuri V. Ivanov, Victor F. Plyusnin, Sergei V. Pashchenko and Sergei F. Vasilevsky* Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation.Fax: +7 3832 342350; e-mail: vasilev@ns.kinetics.nsc.ru Methods for the synthesis of aryl(hetaryl)ethynylphenyl-2-imidazoline nitroxides have been developed; the g-tensor and HFI components for imidazoline-1-oxyl were found to depend (in contrast to imidazoline-3-oxide-1-oxy derivatives) on the properties of substituent at the 2-position.The practical solution of the problem of creating new classes of optical and magnetic materials (molecular ferromagnetics, liquid crystals and photosensitive switches) is hampered by rigid electron and steric requirements on a substrate.1,2 In this context, radicals with triple bonds, in which the coordination centre (a functional group at an aromatic ring or a heteroatom in a heterocycle) and the paramagnetic unit are bound by a rigid phenylacetylene bridge included in the entire molecular conjugation system, are rather promising.The appropriate use of magnetically active compounds considerably depends on the accuracy and completeness of the optical and magnetic parameters of spin-labelled compounds. As far as we know, systematic studies of 2-imidazoline nitroxides by 2 mm band EPR spectroscopy were not conducted.The magnetic parameters of only one derivative of imidazoline-1- oxyl and one imidazoline-3-oxide-1-oxyl were measured.3 In this study, we examined previously unknown acetylene derivatives of nitroxide radicals from the 2-imidazoline series using electronic absorption spectroscopy and 2 mm band EPR spectroscopy.We found for the first time that the substituent at the 2-position of an imidazoline unit poorly influences the magnetic-resonance parameters of imidazoline-3-oxide-1-oxyl. At the same time, components of the g-tensor and HFI constants of imidazoline- 1-oxyl derivatives essentially depend on the nature of the substituent at the 2-position.The structure of spin-labelled acetylenes includes either heterocyclic (p-electron-rich pyrazole and p-electron-deficient pyridine) or p-carbocyclic residues, including a benzocrown ether, and derivatives of 4,4,5,5- tetramethylimidazoline-3-oxide-1-oxyl [nitronylnitroxyl (NN) radicals] and 4,4,5,5-tetramethylimidazoline-1-oxyl [iminonitroxyl (IN) radicals] as stable radical components.NN and IN radicals were produced according to Scheme 1. The synthesis of new nitronylnitroxyls 3a–d was performed by condensation of aldehydes with 2,3-dimethyl-2,3-bis(hydroxylamino) butane and subsequent oxidation of cyclic adducts by sodium periodate. Iminonitroxyls 4a,b were produced by reducing NN radicals 3a,b with sodium nitrite in the presence of glacial acetic acid.† Initial acetylene compounds 2 were obtained via cross-coupling of corresponding ethynyl derivatives 1 with p-bromobenzaldehyde in the presence of Pd(PPh3)2(OAc)2, CuI and NEt3.† The structure of all new compounds were proved by elemental analyses and spectroscopic data. Examples of detailed procedures of synthesis of NN radicals 3b and IN radicals 4b were given below. 2-[4-(6-Methylpyridinyl-3-ethynyl)phenyl]-4,4,5,5-tetramethylimidazoline- 3-oxide-1-oxyl 3b: (1). 1.60 g (0.011 mol) of 2,3-dimethyl-2,3-bis(hydroxylamino)butane in 50 ml of methanol was added at –30 °C to the suspension of 2.21 g (0.01 mol) of aldehyde 2b in 40 ml of methanol. Thereafter, the reaction mixture was mixed up at room temperature for five days and diluted by 40 ml of diethyl ether.The precipitate was filtered, washed out by 20 ml of ether and recrystallised from ethyl acetate. The yield of 1,3-hydroxy- 2-[4-(6-methylpyridinyl-3-ethynyl)phenyl]-4,4,5,5-tetramethylimidazoline (adduct) was 2.84 g (80.9%). Mp 163–165 °C. 1H NMR ([2H6]DMSO) d: 1.04 (s, 6H, Me), 1.09 (s, 6H, Me), 2.51 [s, coincides with a solvent signal, Me (Py)], 7.37 [d, 1H, b-H (Py)], 4.54 [s, 1H, CH (Im)], 7.50– 7.58 (m, 4H, Ph), 7.81 (s, 2H, OH), 7.86 (d, 1H, g-H), 8.65 (d, 1H, a-H).IR (KBr, n/cm–1): 2220 (CºC), 3500 (O–H). Found (%): C, 71.22; H, 7.45; N, 11.46. Calc. for C21H25N3O2 (%): C, 71.77; H, 7.17; N, 11.96. (2). The solution of 0.39 g (0.018 mol) of NaIO4 in 15 ml of water cooled to 10 °C was added by mixing to the suspension of 0.43 g (0.012 mol) of adduct in 15 ml of chloroform.The mixture was stirred for 8 h. The chloroform layer was separated and the water layer was extracted by chloroform (2×15 ml). Organic extracts were dried by CaCl2 and concentrated in vacuo to intimate mass. The residue was chromatographed on silica gel (eluent chloroform). The dark blue oil resulting from eluate distillation was rubbed up with hexane. The forming dark blue crystals were filtered, washed with hexane and recrystallised from a 3:1 hexane–benzene mixture.Yield of 3b was 0.3 g (70.4%). Mp 165–166 °C. IR (KBr, n/cm–1): 2215 (CºC). Found (%): C, 72.68; H, 6.29; N, 12.43. Calc. for C21H22N3O2 (%): C, 72.39; H, 6.36; N, 12.06. 2-[4-(6-Methylpyridinyl-3-ethynyl)phenyl]-4,4,5,5-tetramethylimidazoline- 1-oxyl 4b: 0.60 g (0.0017 mol) of 3b, 0.5 g of NaNO2 and 0.1 ml of glacial acetic acid in 30 ml of chloroform were mixed up upon boiling for 30 min.The reaction mixture was filtered through silica gel. The solvent was distilled in vacuo. The residue was recrystallised thrice with activated coal from hexane. Yield of 4b was 0.41 g (71.6%). Mp 155– 155.5 °C. IR (KBr, n/cm–1): 2228 (CºC). Found (%): C, 75.74; H, 6.62; N, 12.44.Calc. for C21H22N3O2 (%): C, 75.88; H, 6.67; N, 12.64. R C CH 1a–d R C C CHO 2a–d i ii R C C 3a–d N N O O iii R C C 4a,b N N O N N Me Me N Me O O O O O a R = b R = c R = d R = Scheme 1 Reagents and conditions: i, p-bromobenzaldehyde, Pd(OAc)2, CuI, PPh3, NEt3, C6H6, 40–80 °C;4 ii, 2,3-dimethyl-2,3-bis(hydroxylamino)- butane, MeOH, 25 °C, then NaIO4, CH2Cl2, water, 15 °C;5,6 iii, NaNO2, AcOH, CHCl3, 60 °C.5Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) The electronic absorption spectra of NN and IN radicals have two sets of bands in the visible and near-UV regions of the spectrum (Figure 1, Tables 1 and 2).‡ The splitting of both groups (visible and UV regions) is related to the vibrational structure of electronic transitions (characteristic frequencies of 1200–1500 cm–1).The absorption bands of IN radicals are shifted towards a short-wave region to change the colour of these radicals. It should be noted that all NN radicals are blue both in the solid state and in solution, and IN radicals are red. The radicals of the same group with different structures have similar optical absorption spectra.This fact indicates that electronic transitions involve only the groups O–N–C–N–O or O–N–C–N. In the case of NN radicals, an increase in the size of such a group leads to the general shift of bands to the red spectrum region. A set of long-wave absorption bands (peaks at about 16500 cm–1 for NN radicals and 21500 cm–1 for IN radicals) with small molar absorption coefficients refers to n-p* transitions involving the lone electron pairs of oxygen atoms.For many imidazoline nitroxyl radicals with isolated N–O groups, a similar band7 is observed in the region 2400–2100 cm–1. The band in the UV region also has a vibrational structure (peaks at about 30500 cm–1 for NN radicals and 32600 cm–1 for IN radicals). The high intensity of this band allows it to be referred to the resolved p-p*-transition. For imidazoline radicals with isolated N–O groups, this band is also shifted to the short-wave region7 (40500–42500 cm–1).Thus, the UV and visible spectra of all radicals are determined by the presence of groups at which an unpaired electron is delocalised. A fundamental parameter characterising the EPR signals of radicals is g-tensor which depends on the electronic structure and the environment of the radical.In this case, a conventional X-band technique (wavelength of 3 cm and frequency of 9.6 GHz) of determining g-tensors is ineffective because the anisotropy and the mean values of g-tensors for most organic radicals are responsible for the spacing between the lines of different components of about several gauss, which is comparable with the linewidth. The use of a 2 mm wave allows one to get the g-factor resolution up to 10–5 by increasing the Zeeman interaction by one order of magnitude.This accuracy makes it possible to determine all g-tensor components, which are individual parameters of radicals. Figure 2 shows the EPR spectra for the two studied radicals with defined g-tensors and HFI components.The EPR spectra of other radicals have a similar shape.§ The spectra display three lines whose positions are determined by orientations of the magnetic field along each of the principal axes of the gtensor. The positions of the centres of three components allow one to determine the principal values of a g-tensor (gxx, gyy, gzz). The hyperfine interaction with one or two nitrogen nuclei leads to additional splitting of components.In most cases, it is possible ‡ The optical spectra of radical solutions in benzene or toluene (‘cp’ grade) have been recorded on a ‘Specord UV-VIS’ (Karl Zeiss) spectrophotometer using quartz cuvettes with a 0.1–1 cm optical thickness. Radical concentration was varied from 10–4 to 10–3 M. The accuracy of determination of the position of absorption band maxima was ±50 cm–1 and that of extinction coefficients was ±5%.to detect the splitting of a Z-component into five lines upon the interaction with two equivalent nitrogen nuclei (Figure 2, NN radical 3a). If two nitrogen nuclei are non-equivalent (IN radicals), the Z-component splits into seven components (Figure 2, IN radical 4a) owing to the overlapping of two pairs of the lines.Table 3 shows the magnetic resonance parameters of radicals 3a–d, 4a,b, which were obtained by analysing the line positions in 2 mm band EPR spectra. Parameters of the EPR spectra of radicals 3a–d are close to each other; this fact indicates a weak influence of peripheral groups on the orbital of an unpaired electron. The magnetic parameters of IN radicals 4a,b differ considerably from each other and from the parameters of NN radicals.In this case, it is likely that substituents have a strong effect on the behaviour of the unpaired electron. If we approximate the p-system of the symmetric group O–N–C–N–O for the NN radical by the p-system of a pentadienyl radical, the unpaired electron is located on the fourth lower orbital (the total number of electrons is seven), which has the form It can be seen that the p-orbital of the central carbon atom (j3) is not included in the molecular orbital of the unpaired electron.Therefore, the variation of substituents in the group coupled with the p-system via this carbon atom should not have any effect on both the spin density distribution and the change in the spin-Hamiltonian parameters of the radicals.The replacement of carbon atoms by heteroatoms on going from a pentadienyl radical to the group O–N–C–N–O will result in a change in the coefficients of the pairs (j1, j5) and (j2, j4). However, a zero coefficient of j3 will be the same due to the conservation of the plane of symmetry upon this transition. For IN radicals 4a,b, the p-system of the group N–C–N–O can be replaced, as described above, by the p-system of butadiene with five electrons, and the orbital of the unpaired electron will have the form § The EPR spectra were recorded on an 2 mm-band spectrometer (frequency being 130–150 Hz) with a superconducting solenoid produced in the CB of Donetsk Physico-Technological Institute of UAS.Radical solutions in toluene were placed in quartz capillaries with a diameter of 0.3–0.5 mm and length of about 1 cm.The field was calibrated with respect to a standard (Mn2+ in MgO lattice).8 The accuracy of determination of g-tensor components was 7×10–5, that of HFI constants was 0.5 G. The temperature at which the spectra were recorded amounted to 130–140 K. Table 1 Visible spectra of NN and IN radicals.Radical n/cm–1 (e/l mol–1 cm–1) 3a 13900 sh (120) 15200 (295) 16500 (310) 17700 sh (210) 20000 (145) 21500 (135) 3b 13650 sh (60) 15150 (190) 16300 (210) 18300 sh (140) 19900 (145) 21500 (150) 3c 13680 sh (100) 15120 (318) 16300 (350) 17570 sh (230) 19120 sh (100) 3d 13700 sh (110) 15000 (310) 16400 (330) 17700 sh (215) 21500 sh (60) 4a 18900 (340) 20300 (600) 21300 (610) 22800 sh (485) 24000 (515) 25500 sh (540) 4b 18690 (305) 20130 (540) 21420 (560) 22960 (500) 24480 sh (440) 25920 (530) Table 2 Near-UV spectra of NN and IN radicals.Radical n/cm–1 (e/l mol–1 cm–1) 3a 26100 (9800) 29300 (25600) 30500 (29900) 34850 (13300) 3b 26000 (7780) 27000 (4450) 29400 sh (18900) 31000 (29300) 32100 sh (26800) 34200 sh (19800) 3c 25760 (10200) 28720 (33800) 30000 (39700) 31680 sh (30300) 34080 (26200) 35440 (19700) 3d 26000 (12900) 29300 (38500) 33900 sh (19000) 4a 29100 sh (6600) 30900 (27400) 32500 (28000) 34900 sh (20200) 4b 28190 sh (1640) 31000 sh (25200) 32740 (33970) 34400 sh (29590) Table 3 The g-factors and HFI constants of radicals 3a–d, 4a,b.Radical gxx gyy gzz Azz(1) Azz(2) 3a 2.0110 2.00660 2.00210 18.9 18.9 3b 2.0110 2.00660 2.00200 19.3 19.3 3c 2.0110 2.00660 2.00210 18.3 18.3 3d 2.01107 2.00665 2.00205 18.4 18.4 4a 2.00980 2.00607 2.00186 23.0 12.1 4b 2.01070 2.00590 2.00146 30.8 18.6 Y4 = 0.5(j1 – j2 + j4 – j5) (1) Y3 = 0.6(j1 + j4) – 0.37(j2 + j3) (2)Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) In this case, the p-orbital of the carbon atom (j3) is included in the Y3 orbital, and any perturbations in the coupled p-system will have an effect on the wave function of the unpaired electron.For the Y3 function, the spin density at the second centre, which corresponds to the first nitrogen atom, is much smaller than the spin density at the fourth centre (the second nitrogen atom). However, this function corresponds to the butadiene p-system.When changing the Coulomb integrals corresponding to the replacement of carbon atoms by heteroatoms (Da1 ª b, Da2 ª 2b, Da4 ª 2b),9 the exact solution in the framework of the Hueckel approximation or the use of the perturbation theory causes a sharp redistribution of spin density. The perturbation theory gives, for example, the values The spin density is larger at the first nitrogen atom, which corresponds to the large HFI constant Azz(1) compared to Azz(2) for the IN radicals (Table 3).The Azz values of about 33 G are typical of imidazoline radicals with isolated N–O groups.3,10 Lower Azz values for the NN and IN radicals are related to a decreased spin density at nitrogen atoms in more extended systems. It is well known that the deviation of gxx components from the g-factor for a free electron can be estimated by the formula3 where l is the spin–orbital coupling constant for an oxygen atom (ª 70 cm–1 for a free atom), rpO is the spin density at the oxygen atom and DEnp* is the energy of the long-wave n–p* transition (Table 1).Even with rpO ª 1 and DEnp* ª 16500 cm–1 (Table 1), Dgxx ª 4.2×10–3; this value is lower than the experimental value (Dgxx ª 8.7×10–3) for NN radicals by a factor of two. If we take into account both a decrease in the spin–orbital coupling in the molecules compared to that in isolated atoms and the rpO values really lower than unity, the difference between Dgxx calculated by formula (4) and the experimental values increases.This disagreement can be due to the lowerenergy excited states, the transition to which is forbidden by both symmetry and spin, and which are not manifested in the optical spectra.Thus, a decrease in the g-factor upon the transition from NN to IN radicals can be caused by both a change in the spin density rpO and an increase in the energy of transition into the state defreezing the orbital moment. Of course, the accurate determination of the electronic structure and geometry of radicals from the experimental values of magnetic parameters (g-factors and HFI constants) needs further quantum-chemical calculations.This work was supported by the Russian Foundation for Basic Research (grant nos. 98-03-32908a and 96-03-33495a), the Ministry of Education (a grant in natural sciences, 1998– 1999), the Siberian Branch of the Russian Academy of Sciences (grant no. 97-N35 and grant for young scientists no. N347-1998) and the Russian Federal Programme ‘Integration of the Higher School and Science’ (grant no. 274). References 1 P. Wautelet, A. Bieber, P. Turec, J. Moigne and J. Andre, Mol. Cryst. Liq. Cryst., 1997, 305, 55. 2 L. B. Voldarsky, V. A. Reznikov and V. I. Ovcharenko, Synthetic Chemistry of Stable Nitroxides, CRC Press, Boca Raton, 1994, p. 221. 3 V. I. Gulin, S. A. Dikanov, Yu. D. Tsvetkov, I. A. Grigor’ev and I. A. Kirilyuk, Zh. Strukt. Khim., 1988, 29, 139 [J. Struct. Chem. (Engl. Transl.), 1988, 29, 472]. 4 S. F. Vasilevsky and E. V. Tretyakov, Izv. Akad. Nauk., Ser. Khim., in press. 5 E. F. Ulman, L. Call and J. H. Osiecki, J. Org. Chem., 1970, 35, 3623. 6 E. F. Ulman, J. H. Osiecki, D. G. B. Boocock and R. Darcy, J. Am. Chem. Soc., 1972, 94, 7049. 7 L. B. Volodarskii, I. A. Grigor’ev, S. A. Dikanov, V. A. Reznikov and G. I. Shchukin, Imidazolinovye nitroksil’nye radikaly (Imidazoline nitroxyl radicals), Nauka, Novosibirsk, 1988, p. 216 (in Russian). 8 O. Burghaus, M. Plato, M. Rohrer, K. Mobius, F. MacMillan and W. Lubitz, J. Phys. Chem., 1993, 97, 7639. 9 (a) M. A. Ondar, O. Ya. Grinberg, A. A. Dubinskii, A. F. Shestakov and Ya. S. Lebedev, Khim. Fiz., 1983, 1, 54 (in Russian); (b) M. A. Ondar, O. Ya. Grinberg, A. A. Dubinskii and Ya. S. Lebedev, Khim. Fiz., 1984, 3, 527 (in Russian). 10 G. J. Wolga and R. Tseng, Phys. Rev., 1964, 133, 1563. 30 20 10 0 35 30 25 20 15 n/103 cm–1 e/103 l mol–1 cm–1 4a 3a ×20 Figure 1 Electronic absorption spectra of nitroxyl radicals 3a and 4a in benzene. 3a 4a r1 = r0 = 0.69, r2 = rN1 = 0.107, r3 = rC = 0.18, r4 = rN2 = 0.023 (3) Dgxx = (4) ~ lrO p DEnp* 3a 4a gx gy gz Mn2+ Azz(1) Azz(2) gz gy gx Azz(1) Azz(2) 4600 4610 4620 4630 4640 H0/mT Figure 2 2 mm band EPR spectra of radicals 3a and 4a (5×10–5 M) in oxygen-free toluene at 130–140 K. Received: 9th December 1998; Com. 98/1409

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Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) Preparation of carbon-coated alumina by pyrolysis of adsorbed acetylacetone Lyudmila F. Sharanda,a Yuri V. Plyuto,*a Igor V. Babich,a,c Yana A. Babichb and Jacob A. Moulijnc a Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 252022 Kiev, Ukraine. E-mail: user@surfchem.freenet.kiev.ua b A. V. Dumansky Institute of Colloid and Water Chemistry, National Academy of Sciences of Ukraine, 252680 Kiev, Ukraine c Department of Chemical Engineering, Delft University of Technology, 2628 BL Delft, The Netherlands A carbon coating has been prepared on the surface of an alumina support by pyrolysis of adsorbed acetylacetone. Carbon-coated silica and alumina supports are promising for application in catalysis and chromatography.1–5 Therefore much efforts are being made in order to achieve a desired combination of the physico-chemical properties of both components in novel materials.The main factors affecting the structure of a carbon coating on the support surface are the chemical nature of the carbon precursor and the conditions of its pyrolysis.1–6 This work aims at the development of a novel method for coating alumina supports with carbon and the physico-chemical characterization of the designed materials.Carbon-coated alumina was synthesised by adsorption and subsequent pyrolysis of acetylacetone on the support surface. Acetylacetone was selected due to its ability to form surface aluminium acetylacetonate complexes.7–9 The mechanism of carbon coating deposition and the structure of the prepared samples were monitored by IR, XRD, TG/DTG–DTA, TEM and adsorption measurements.Precipitated alumina [CK 300, Ketjen, SBET(N2) = 259 m2 g–1] was used as a support. The as-received support was crushed and sieved to a particle size of 0.25–0.50 mm. A sample was placed in a McBain quartz spring balance and evacuated at 200 °C and 1×10–2 Pa for 3 h prior to the adsorption of acetylacetone.After cooling to room temperature, the sample was contacted with saturated vapour of acetylacetone up to reaching the adsorption equilibrium (10–12 h). Afterwards, the sample was evacuated at room temperature to a pressure of 1×10–2 Pa to remove an excess of acetylacetone. Then, the sample temperature was increased to 700 °C within 5–6 h under continuous pumping.The sample was kept at this temperature and a pressure of 1×10–2 Pa for 1 h in order to complete the pyrolysis of the adsorbed acetylacetone and to remove volatile products. To prepare samples with an increased carbon content, the adsorption–pyrolysis cycle was repeated up to three times. The above procedure resulted in samples with the carbon content 2.6, 4.6 and 6.3 wt%, denoted hereafter as C(2.6)/Al2O3, C(4.6)/Al2O3 and C(6.3)/Al2O3, respectively. The carbon content of the samples was determined by gravimetry with a McBain quartz spring balance by calcination at 700 °C for 4 h in air.Adsorption measurements showed that the contact of the initial alumina with acetylacetone resulted in the strong interaction with the support surface.After evacuation at room temperature, the carbon loading in surface acetylacetonate complexes was found to be 16.6 C at nm–2 (Table 1). The carbon loading in the sample after pyrolysis was 5.3 C at nm–2, which corresponds to 31.6% carbon yield. Sample C(2.6)/Al2O3 was brought into contact with acetylacetone vapour again. The adsorption of acetylacetone appeared to be somewhat higher as compared with that on the initial alumina support and corresponded to carbon loading in surface acetylacetonate complexes of 20.9 C at nm–2.Nevertheless, the carbon yield after pyrolysis was lower and approached 19.6%. The carbon loading in sample C(4.6)/Al2O3 was found to be 9.4 C at nm–2. Table 1 demonstrates that the repetition of the adsorption– pyrolysis cycles resulted in an increase in the carbon content of the samples.Although acetylacetone adsorption increased in each consecutive adsorption cycle, the carbon yield after pyrolysis behaved in the reverse order. IR spectroscopy confirmed a strong interaction of acetylacetone with the initial alumina support (Figure 1, curve 2). The distinct IR bands at 1550, 1535 and especially 1295 cm–1, which are typical of surface aluminium acetylacetonate complexes,7–9 are observed.These complexes resulted from the interaction of acetylacetone with the coordinatively unsaturated Al3+ sites.8,9 Moreover, the IR bands at 1595, 1468 and 1405 cm–1 derived from the adsorbed acetylacetone8 are clearly seen. The IR bands at 1727 and 1707 cm–1, characteristic of the keto form of acetylacetone,10 are not observed.Therefore, we can conclude that a shift of the keto–enol equilibrium occurred upon the adsorption, and acetylacetone was present on the alumina surface preferably in the enol form. The pyrolysis resulted in degradation of surface aluminium acetylacetonate complexes, which is accompanied by the disappearance of the above bands in the IR spectrum (see Figure 1, curve 3).The IR bands at 1620, 1570 and 1400 cm–1 are seen, of which that at 1570 cm–1 can be attributed to carboxyl groups in the carbon coating.11,12 The adsorption of acetylacetone on sample C(2.6)/Al2O3 (Figure 1, curve 4) occurs similarly to the case of the initial alumina support. The main difference between the interaction of acetylacetone with the Al2O3 support and sample C(2.6)/ Al2O3 concerns the low-frequency shift of all IR bands in the latter case, which reflects a change in the nature of the adsorption sites due to the shielding of the alumina surface with the deposited carbon.The adsorption of acetylacetone on sample C(4.6)/Al2O3 (Figure 1, curve 5) is completely different from that on C(2.6)/ Al2O3.The difference consists in the absence of the IR band at 1285 cm–1, which is typical of surface aluminium acetylacetonate complexes.7,9 This means that aluminium sites are no longer involved in the interaction with acetylacetone molecules. In other words, in sample C(4.6)/Al2O3, the carbon coating completely blocks or shields the coordinatively unsaturated Al3+ sites. Table 1 Preparation of carbon-coated alumina supports.Sample Initial carbon content (wt%) Adsorbed Hacac/ C at nm–2 Pyrolysis of adsorbed Hacac Carbon yield (%) Increase of carbon content/ C at nm–2 Final carbon content C at nm–2 wt% Al2O3 0 16.6 31.6 5.3 5.3 2.6 C(2.6)/Al2O3 2.6 20.9 19.6 4.1 9.4 4.6 C(4.6)/Al2O3 4.6 36.2 10.2 3.7 13.1 6.3 C(6.3)/Al2O3 6.3 40.2 8.1 3.3 16.4 7.8 aVhexane and Vwater correspond to the amounts of adsorbed hexane and water, respectively, converted to liquid volume. Table 2 Textural and surface properties of carbon coated alumina supports.Sample Pore volume/ cm3 g–1 Vhexane/Va water (p/p0 = 0.05) SBET(N2)/m2 g–1 Al2O3 0.64 1.00 259 C(2.6)/Al2O3 0.62 1.37 241 C(4.6)/Al2O3 0.61 1.40 241 C(6.3)/Al2O3 0.59 1.57 241Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) The IR spectrum of sample C(6.3)/Al2O3 (Figure 1, curve 6) is similar to that of C(4.6)/Al2O3 (Figure 1, curve 5) and confirms the proposed mechanism of the adsorption of acetylacetone on a carbon-coated alumina support. Characterization of the samples using XRD did not reveal any peaks which should be attributed to ordered carbon structures.13 Therefore, the presence of either an amorphous carbon coating or a thin graphite layer can be assumed.Regardless of the carbon content, the thermoanalytical characterization of the samples in air exhibits the intense weight loss in DTG patterns around 500 °C, which coincides with the exothermic peak in DTA curves. The oxidation proceeds in one step in a narrow temperature range.This suggests that degradation of a single carbon phase occurs. Moreover, no separate carbon phase is observed in the TEM images of the samples. Therefore, we may suppose that carbon uniformly coats the alumina surface. The shape of the nitrogen adsorption–desorption isotherms and the hysteresis loops were found to be similar for all samples. The pore volume and the apparent surface area of all carbon-coated samples appeared to be somewhat less than those of the initial alumina support (Table 2). This means that the porous structure of the initial alumina support was not changed upon carbon deposition.Moreover, a pore mouth plugging did not occur, and carbon appeared to be uniformly distributed over the surface of the alumina support. The adsorption isotherms of hexane and water were measured in order to evaluate the influence of the carbon coating on the hydrophilicity of the initial alumina support.The difference between the hexane and water adsorption is most pronounced at low p/p0. At p/p0 of 0.05, the hexane-to-water adsorption ratio increases from 1 for the initial alumina to 1.57 for sample C(6.3)/Al2O3 (Table 2).This means a progressive decrease in the hydrophilicity of carbon-coated samples and hence an increase in the alumina coverage with carbon upon increasing carbon content. In summary, a carbon coating on alumina supports can be prepared by pyrolysis of adsorbed acetylacetone. The carbon content can be increased by the repetition of acetylacetone adsorption–pyrolysis cycles. The carbon coating does not influence the pore structure of the initial alumina support but decreases its hydrophilicity.Carbon appears to be uniformly distributed on the support surface whose coverage increases with an increase in the carbon loading. This results in almost complete shielding of the alumina surface at a carbon loading of 13.1 C at nm–2. This work was supported in part by INTAS (grant no.UA- 95-140). References 1 K. Kamegawa and H. Yoshida, J. Colloid Interface Sci., 1993, 159, 324. 2 P. R. Vissers, F. P. M. Mercx, S. M. A. M. Bouwens, V. H. J. de Beer, and R. Prins, J. Catal., 1988, 114, 291. 3 T. Zhang, P. D. Jacobs and H. W. Haynes, Jr., Catal. Today, 1994, 19, 353. 4 R.Leboda, Chromatographia, 1981, 14, 524. 5 K. Bebris, A. V. Kiselev, Yu.S. Nikitin, I. I. Frolov, L. V. Tarasova and Ya. I. Yashin, Chromatographia, 1978, 11, 206. 6 Th. Vergunst, F. Kapteijn and J. A. Moulijn, in Preparation of Catalysts VII, eds. B. Delmon, P. A. Jacobs, R. Maggi, J. A. Martens, P. Grange and G. Poncelet, Elsevier, Amsterdam, 1998, vol. 118, p. 175. 7 J. A. R. van Veen, G. Jonkers and W. H. Hesselink, J. Chem. Soc., Faraday Trans., 1989, 85, 389. 8 M.Alexander, D. M. Bibby, R. F. Howe and R. H. Meinhold, Zeolites, 1993, 13, 441. 9 A. Kytokivi, A. Rautiainen and A. Root, J. Chem. Soc., Faraday Trans., 1997, 93, 4079. 10 R. Mecke and E. Z. Funck, Electrochemie, 1956, 60, 1124. 11 J. A. R. van Veen, P. C. de Jong-Versloot, G. M. M. van Kessel and F. J. Fels, Thermochim. Acta, 1989, 152, 359. 12 T. J. Bandosz, J. Jagiello and J. A. Schwarz, Langmuir, 1996, 12, 6480. 13 J. V. Sanders, J. A. Spink and S. S. Pollack, Appl. Catal., 1983, 5, 65. Transmittance n/cm–1 1 2 3 4 5 6 7 1800 1500 1200 1570 1620 1580 1520 1390 1580 1285 1400 1295 1468 1405 1535 1550 1595 1640 1520 1390 1580 1520 1390 1620 1570 Figure 1 IR spectra of alumina supports at different stages of coating with carbon: (1) initial Al2O3; (2) Al2O3 with adsorbed acetylacetone; (3) sample C(2.6)/Al2O3; (4) sample C(2.6)/Al2O3 with adsorbed acetylacetone; (5) sample C(4.6)/Al2O3 with adsorbed acetylacetone; (6) sample C(6.3)/Al2O3 with adsorbed acetylacetone; (7) sample C(6.3)/Al2O3 sample with adsorbed acetylacetone subjected to pyrolysis. Received: 5th November 1998; Com. 98/1396 (8/08672I)

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Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) Transients of current at the adsorption of carbon monoxide on platinum and palladium electrodes Boris I. Podlovchenko,* Tatyana D. Gladysheva and Aleksandr V. Smolin Department of Chemistry, M. V. Lomonosov Moscow State University, 119899 Moscow, Russian Federation. Fax: +7 095 939 0171; e-mail: podlov@elch.chem.msu.ru The analysis of the I vs.t curves obtained during the adsorption of CO on Pt and Pd in 0.5 M H2SO4 was carried out by using the thermodynamic concept of the electrode total charge. Important information on the mechanism of the processes taking place at the contact of electrodes with surface-active substances can be obtained on the basis of the analysis of transients of current (at a constant potential) and potential (at open circuit).1–3 After CO was brought into contact with Pt and Pd electrodeposits at open circuit potentials stabilised in the double layer region, the potential shifted only in the negative direction.4,5 This effect was explained by the oxidation of CO.Negative potential shifts at open circuit should correspond to anodic potentiostatic current transients. However, introduction of CO into contact with a single-crystal Pt and polycrystalline smooth platinum at a constant potential 0.3 £ Er ads £0.5 V† in acid solutions led to cathodic current transients.6,7 The authors explained this by processes of the following type: Pt+–A– + + CO + e–®Pt–CO + A– (where A– is an anion) and assumed that CO is not oxidised at Er < 0.5 V.Potentiostatic current transients were measured in 0.5 M H2SO4 after CO was brought into contact with a thin Pd layer electrodeposited on Au.8 The author observed cathodic currents at Er ads > 0.18 V and anodic currents at Er ads < 0.18 V. This allowed him to conclude that the potential of the zero total charge (pztc) in the presence of COads is 0.18 ± 0.02 V.Thus, the literature data on the form of transients of current and open-circuit potential during the adsorption of CO, as well as their explanation are contradictory. It was interesting to carry out more systematic and comprehensive studies, both theoretical and experimental, of the possibility of using current transients for characterising the adsorption of uncharged species on electrodes of platinum-group metals. The choice of Pt and Pd electrodeposits as the electrode materials was to a large degree caused by the fact that the structure of the electrical double layer is studied sufficiently well on these electrodes and, particularly, their pztc are known.9–12 † The potential values, Er, refer to the reversible hydrogen electrode in the same solution.The electrodeposition of Pt and Pd (5 to 10 mg cm–2) was carried out from 2% (w/v) H2PtCl6 and 1% (w/v) PdCl2 + + 0.5M H2SO4 solutions under potentiostatic conditions at Er = 0.25 V.13,14 The specific surface areas of the deposits ranged from 8 to 18 m2 g–1.Carbon monoxide contained: CO 99.72 wt%, CO2 0.23 wt%, O2 and H2 < 10 ppm. For purification of the gas from CO2, we used tubes filled with Ascarite.The studies were carried out at 18–20 °C in a three-electrode glass cell with separate anodic and cathodic compartments. For measuring potentiostatic transients (I–t curves), the supporting electrolyte solution was changed for a solution saturated with CO at a fixed potential Er ads without breaking the circuit (the CO flow through the solution continued).The thermodynamic theory of the reversible hydrogen electrode developed by Frumkin9 serves as the theoretical basis for analysing the transients of current when uncharged species are adsorbed in the potential region where they do not undergo any faradaic transformations. If these species are CO molecules, then, during their chemisorption at Er ads on the metals that reversibly adsorb ions, hydrogen and oxygen, the following relationships should be fulfilled: where DQ' is the charge consumed in the formation of a COads monolayer at a fixed Er ads; Q'M and Q'CO/M are the total charges of the metal electrode in the absence and in the presence COads monolayer on the surface; Cb and CCO are polarisation capacities of the electrode in the supporting electrolyte solution before and after CO adsorption; Er,Q' = 0 and ECO r,Q' = 0 are the potentials of the zero total charge in the absence and in the presence of COads monolayer.In potentiostatic transients at Er ads = 0.4 and 0.5 V (Figure 1, curves 3 and 4), in the first moment after CO was introduced, the cathodic currents are observed. However, with time, the cathodic currents change to small anodic currents, which suggest slow but quite noticeable electrooxidation of CO on Pt/Pt during the adsorption at the considered potentials (this does not agree with the published data6,7).In Figure 1, curve 1 (Er ads = = 0.2 V), only anodic currents are observed, which, by the large, are determined by the hydrogen displacement from the electrode surface.3,6,7 As it follows from expressions (1), if CO is adsorbed as a ‘neutral’ species, zero currents should be observed at those Er ads at which the electrode total charges in the absence (Q'M) and in the presence (Q'CO/M) of COads are equal.The potential Er = 0.3 V corresponds approximately to the value Er,Q' = 0 of a Pt/Pt electrode in 0.5 M H2SO4.9 The value DQcat (Figure 1, curve 2), which corresponds to Er ads equal to 0.3 V, is very small, which allows us to suggest that the potential of the zero total charge changes relatively little during the CO chemisorption.13 The data obtained lead us to conclude that, in the case of Pt/Pt, the value of DQcat that corresponds to the current transients at Er ads of 0.4 V and 0.5 V (Figure 1) is determined not only by displacement of anions from the Pt surface by CO molecules,6,7 I t 100 mA 10 min 1 2 3 4 5 Figure 1 I vs.t curves obtained after CO was brought into contact with Pt/Pt under potentiostatic conditions in 0.5 M H2SO4 at different Er: (1) 0.2, (2) 0.3, (3) 0.4, (4) 0.5 and (5) 0.6 V. DQ' = Q'CO/M – Q'M DQ' = CCOdEr – CbdEr , Er ads Er,Q' = 0 CO ò Er ads Er,Q' = 0 CO ò (1) (1a)Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) but also by other processes. Indeed, the capacity value found in the presence of a monolayer of COads on the surface (26 mF cm–2) is close to the value of the ionic component of the polarisation capacity of a Pt/Pt electrode in 0.5 M H2SO4 (35–40 mF cm–2).10 About a half of the total value of the polarisation capacity of Pt/Pt (Cb = 70–80 mF cm–2) falls to adsorbed hydrogen and for oxygen.9–11 We can conclude that, on Pt/Pt at Er ads in the ‘double-layer’ region, the decrease in the polarisation capacity and the corresponding cathodic currents observed during the CO adsorption are determined by the displacement of both anions and adsorbed hydrogen and/or oxygen. Potentiostatic transients measured after CO was brought into contact with a Pd electrode at the potentials of the double-layer region (Er ads = 0.3–0.65 V) are characterised by pronounced cathodic currents (Figure 2).The charges DQcat that should be passed to the electrode in order to keep the potential constant, calculated per 1 cm2 of the true surface area are vastly greater into absolute value than those of Pt/Pt. The cathodic current drops to zero in 15–20 min and does not change to an anodic current.This allowed us to assume that CO is not noticeably oxidised on Pd at Er £ 0.65 V. Hence, the Pd–CO system is more convenient than Pt–CO for the interpretation of the current transients on the basis of the concept of the total electrode charge [see expressions (1) and (1a)]. From galvanostatic curves, we estimated the capacity of electrodeposited Pd in the Er interval from 0.4 to 0.8 V in the absence and in the presence of a COads monolayer.The values of Cb and CCO were 33±2 and 9.4±0.4 mF cm–2, respectively. The substantial decrease in the capacity of a Pd electrode in the presence of CO, apparently, is associated with a decrease in the dielectric constant of the double layer and an increase in the distance between the ionic plane of the double layer and the metal surface.If assumed that Q'Pd = 0 at Er = 0.3V,9,12 by integrating curve 1 in Figure 2, we obtain that the value Q'CO/Pd at Er = = 0.3 V is 48±4 mC cm–2. Such a high absolute value of Q'CO/Pd at 0.3 V is only possible if the value of ECO r,Q' = 0 is very high (> 0.8 V). An alternative way of explaining the cathodic currents when Er ads is constant may be the assumption of the partial reduction of COads at the double-layer potentials.8 However, spectral methods did not show any reduced forms of CO on the Pd surface.14 Moreover, according to our measurements, the values of DQ' in the Er interval from 0.3 to 0.65 V did not change with Er ads within the reproducibility limits.If, as in ref. 8, we assume that the cathodic currents are determined by the formation of reduced forms of COads, the independence of DQ' of Er is very hard to explain. Thus, if we consider CO as a neutral species, then the transients of current and Er observed suggest that, in the double-layer potential region, the presence of COads changes the sign of the Pd surface charge from positive to negative.Preferential adsorption of anions should change to the preferential adsorption of cations. Probably, this is caused by the adsorption of CO in the form of dipoles oriented with the positive end to the surface. After CO was brought into contact with a Pd/Pt electrode at Er ads = 0.09 V, substantial anodic currents appeared (Figure 2, curve 3) which we assumed are due to ionisation of Hads displaced by chemisorbed CO molecules. This work was supported by the Russian Foundation for Basic Research (grant no. 99-03-32360a). References 1 A. D. Obrucheva, Dokl. Akad. Nauk SSSR, 1961, 141, 1413 [Dokl. Phys. Chem. (Engl. Transl.), 1961, 141, 649]. 2 B. E. Conway, B. MacDougal and H. Angerstein-Kozlowska, J. Chem. Soc., Faraday Trans., 1972, 68, 1565. 3 M. W. Breiter, J. Phys. Chem., 1968, 70, 1305. 4 G. L. Padyukova, A. B. Fasman and D. V. Sokolskii, Elektrokhimiya, 1966, 2, 885 [Sov. Electrochem. (Engl. Transl.), 1966, 2, 823]. 5 A. B. Fasman, Z. N. Novikova and D. V. Sokolskii, Zh. Fiz. Khim., 1966, 40, 556 (Russ. J. Phys. Chem., 1966, 40, 299). 6 J. M. Orts, K. Gomez, J. M. Feliu and J. Clavilier, Electrochim. Acta, 1994, 39,1519. 7 J. Clavilier, J. M. Orts, R. Gomez, J. M. Feliu and A. Aldaz, J. Electroanal. Chem., 1996, 404, 281. 8 A. Czerwinski, J. Electroanal. Chem., 1994, 379, 487. 9 A. N. Frumkin, Potentsialy nulevogo zaryada (Potentials of Zero Charge), Nauka, Moscow, 1979 (in Russian). 10 O. A. Petrii and D. A. Sveshnikova, Elektrokhimiya, 1976, 12, 985 [Sov. Electrochem. (Engl. Transl.), 1976, 12, 912]. 11 B. I. Podlovchenko, T. D. Gladysheva, O. Vyaznikovtseva and Ju. M. Vol’fkovich, Electrokhimiya, 1983, 19, 424 [Sov. Electrochem. (Engl. Transl.), 1983, 19, 381]. 12 V. V. Topolev and O. A. Petrii, Elektrokhimiya, 1970, 6, 1726 [Sov. Electrochem. (Engl. Transl.), 1970, 6, 1651]. 13 A. N. Frumkin, V. E. Kazarinov and G. Ya. Tysyachnaya, Dokl. Akad. Nauk SSSR, 1971, 198, 145 [Dokl. Phys. Chem. (Engl. Transl.), 1971, 198, 13]. 14 K. Yoshioka, F. Kitamura, M. Takeda, M. Takahashi and M. Ito, Surf. Sci., 1990, 222, 90. 100 60 20 –20 –60 0 10 20 30 t/min I/mA Figure 2 Potentiostatic current transient measured after CO was introduced into contact with Pd/Pt in 0.5 M H2SO4 at different Er: (1) 0.65, (2) 0.30 and (3) 0.09 V. 1 2 3 Received: 28th November 1998; Com. 98/1403 (8/09463B)

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Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) Synthesis of (alk-1-ynyl)cyclopropenium salts via the reaction of (alk-1-ynyl)chlorocarbenes with diphenylacetylene Konstantin N. Shavrin,* Valentin D. Gvozdev and Oleg M. Nefedov N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow, Russian Federation. Fax: +7 095 135 5328; e-mail: gvozdev@ufn.ioc.ac.ru 1-(Alk-1-ynyl)-2,3-diphenylcyclopropenium perchlorates 7 have been prepared via the generation of (alk-1-ynyl)chlorocarbenes 3 from 1,1-dichloroalk-2-ynes 1 or 3-bromo-1,1,1-trichloro-3-phenylpropane 2 by the interaction with ButOK in the presence of tolan followed by the treatment of the reaction mixture with perchloric acid, whereas the treatment of the reaction mixture with HBr resulted in (2-bromoalk-1-enyl)cyclopropenium bromides 9. Previously we have discovered a new class of carbenic species, (alk-1-ynyl)halocarbenes, and their ability to add to double bonds of alkenes with the formation of corresponding 1-(alk- 1-ynyl)halocyclopropanes.1–5 At the same time, any data on the ability of these carbenes to react with alkynes are not available. Special interest in these reactions can be explained by the possibility of formation, analogously to halo(phenyl)carbenes,6 of (alk-1-ynyl)-substituted cyclopropenium salts, previously unknown acetylenic compounds with the conjugation between the carbon–carbon triple bond and the cyclopropenium cation.We have found that the reaction of ButOK with 1,1-dichloroalk- 2-ynes 1a–c or 3-bromo-1,1,1-trichloro-3-phenylpropane 2 in benzene in the presence of a three-fold molar excess of tolan at ~20 °C (Scheme 1) followed by the treatment of the reaction mixture (passed trough SiO2 or washed with water) with 75% perchloric acid (method A) results in solid (alk-1-ynyl)cyclopropenium perchlorates 7† in 24–38% yields.Under the treatment of the reaction mixture with gaseous HBr (method B) or a 48% aqueous HBr solution (method C), (2-bromoalk-1-enyl)- cyclopropenium bromides 9a–c‡ were isolated in 23–37% yields.Cyclopropenium bromide 9a was identified as a Z-isomer, and cyclopropenium bromides 9b and 9c, as mixtures of Z- and Eisomers. The configuration of double bonds in salts 9a–c was determined by a comparative analysis of the chemical shifts of ortho-protons in phenyl groups attached to the three-membered ring.† NMR spectra were measured on a Bruker AC200p spectrometer (200 and 50 MHz for 1H and 13C spectra, respectively) using solutions of the test compounds in CD3CN. IR spectra were recorded on a Bruker IFS-113V spectrometer. All new compounds 7a–c gave expected spectral data. For 7a: 38% yield from 4,4-dimethyl-1,1-dichloropent-2-yne 1a, method A; mp 70– 71 °C. 1H NMR, d: 1.54 (s, 9H, But), 7.86 (br. dd, 4H, meta-H, 2Ph, J 7.8 Hz, J 7.8 Hz), 8.04 (br. t, 2H, para-H, 2Ph, J 7.8 Hz), 8.43 (br. d, 4H, ortho-H, 2Ph, J 7.8 Hz). 13C NMR, d: 28.6 (3Me), 30.2 (CMe3), 63.9 (ButCºC), 119.4 (ipso-C, 2Ph), 130.4, 136.1 and 139.2 (2Ph), 138.4 (ButCºC), 144.2 (CCºC, cyclo-C3 +), 155.3 (2CPh, cyclo-C3 +).IR (powder, n/cm–1): 1408 (cyclo-C3 + ), 2210 (CºC). For 7b: 35% yield from 1,1-dichloro-3-phenylprop-2-yne 1b, method A; mp 66–68 °C. 1H NMR, d: 7.69 (br. dd, 2H, meta-H, PhCº, J 7.5 Hz, J 7.5 Hz), 7.80 (br. t, 1H, para-H, PhCº, J 7.5 Hz), 7.93 (br. dd, 4H, meta-H, 2Ph, J 7.7 Hz, J 7.7 Hz), 8.0–8.15 (m, 4H, para-H, 2Ph, ortho-H, PhCº), 8.53 (br. d, 4H, ortho-H, 2Ph, J 7.7 Hz). 13C NMR d: 73.5 (PhCºC), 118.2 and 119.5 (ipso-C, 2Ph, PhCº), 129.5, 134.4 and 134.9 (PhCº), 130.4, 136.2 and 139.2 (2Ph), 125.7 (PhCºC), 142.4 (CCºC, cyclo-C3 +), 154.5 (2CPh, cyclo-C3 + ). IR (powder, n/cm–1): 1408 (cyclo-C3 + ), 2191 (CºC). Perchlorate 7b was also obtained in 25% yield by method A from 3-bromo-3-phenyl-1,1,1-trichloropropane 2, which, according to ref. 4, generates (phenylethynyl)chlorocarbene under the action of ButOK.For 7c: 24% yield from 1,1-dichloro-3-(p-tolyl)prop-2-yne 1c, method A; mp 163–164 °C. 1H NMR d: 2.49 (s, 3H, Me), 7.48 (br. d, 2H, meta- H, p-tolyl, J 8.0 Hz), 7.91 (br. dd, 4H, meta-H, 2Ph, J 7.6 Hz, J 7.6 Hz), 7.92 (br. d, 2H, ortho-H, p-tolyl, J 8.0 Hz), 8.08 (br. t, 2H, para-H, 2Ph, J 7.6 Hz), 8.51 (br. d, 4H, ortho-H, 2Ph, J 7.6 Hz). 13C NMR d: 21.3 (Me), 73.9 (p-tolylCºC), 115.1 and 119.6 (ipso-C, 2Ph, p-tolyl); 130.3, 130.5, 135.1, 136.1 and 139.1 (2Ph, p-tolyl), 127.2 (p-tolylCºC), 142.2 (CCºC, cyclo-C3 + ), 146.5 (CMe, p-tolyl), 153.9 (2CPh, cyclo-C3 +). ‡ For the Z-isomer of 9a: 38% yield from 1,1-dichloro-4,4-dimethylpent- 2-yne 1a, method B; mp 75–76 °C. 1H NMR d: 1.49 (s, 9H, But), 7.87 (br.dd, 4H, meta-H, 2Ph, J 7.8 Hz, J 7.8 Hz), 7.93 (s, 1H, CH=), 8.02 (br. t, 2H, para-H, 2Ph, J 7.8 Hz), 8.52 (br. d, 4H, ortho-H, 2Ph, J 7.8 Hz). 13C NMR (without decoupling) d: 28.6 (q. sept., 3Me, J 129 Hz, J 5 Hz), 43.0 (m, CMe3), 111.8 (d, CH=, J 172 Hz), 119.9 (t, ipso-C, Ph, J 9 Hz), 129.9 (dd, ortho-C, Ph, J 166 Hz, J 8 Hz), 136.2 (dd, meta-C, Ph, J 165 Hz, J 7 Hz, J 7 Hz), 138.1 (dt, para-C, Ph, J 165 Hz, J 7 Hz), 153.2 (d, C–CH=, cyclo-C3 +, J 2 Hz), 156.6 (d, CBr=, J 5 Hz), 171.2 (s, 2CPh, cyclo-C3 + ). IR (powder, n/cm–1): 1416 (cyclo-C3 +).For 9b: 23% yield from 1,1-dichloro-3-(p-tolyl)prop-2-yne 1c, method B; mixture of Z- and E-isomers (Z/E ratio 1.4:1). Z-isomer: 1H NMR d: 2.50 (s, 3H, Me), 7.46 (d, 2H, meta-H, p-tolyl, J 7.9 Hz), 7.69 (d, 2H, ortho-H, p-tolyl, J 7.9 Hz), 7.89 (br.dd, 4H, meta-H, 2Ph, J 7.6 Hz, J 7.6 Hz), 7.98–8.15 (m, 2H, para-H, 2Ph), 8.40 (s, 1H, CH–), 8.55 (br. d, 4H, ortho-H, 2Ph, J 7.6 Hz). E-isomer: 1H NMR d: 2.22 (s, 3H, Me), 7.21 (d, 2H, meta-H, p-tolyl, J 7.9 Hz), 7.53 (d, 2H, ortho-H, p-tolyl, J 7.9 Hz), 7.88 (br. dd, 4H, meta-H, 2Ph, J 7.6 Hz, J 7.6 Hz), 7.98–8.15 (m, 7H, para-H and ortho-H, 2Ph, CH=).IR (powder, n/cm–1): 1404 (cyclo-C3 +). a R = But b R = Ph c R = p-tolyl Scheme 1 Reagents and conditions: i, ButOK, benzene, 20 °C; ii, 75% aqueous HClO4 (method A), benzene, 20 °C; iii, gaseous HBr (method B) or 48% aqueous HBr (method C), benzene, 20 °C. RC CCHCl 2 PhCHBrCH 2CCl3 1a–c 2 i RC CCCl 3a–c PhC CPh Ph Ph R Cl Ph Ph R Cl 4a–c i Ph Ph R ButO 5a–c Ph R ButO Ph 6a–c Ph Ph H Br R Br 9a–c Ph Ph Br 8a–c Ph Ph ClO4 7a–c iii iii ii R RMendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) The formation of cyclopropenium salts 7a–c and 9a–c proceeds, according to Scheme 1. (Alk-1-ynyl)halocarbenes1–4 3 generated by the reaction of halides 1a–c or 2 with ButOK add to the triple bond of tolan to form chlorides 4a–c, which react with ButOK under the reaction conditions with the formation of corresponding isomeric ethers 5a–c and 6a–c.These ethers give (alk-1-ynyl)cyclopropenium perchlorates 7a–c on the treatment with HClO4 and (2-bromoalk-1-enyl)cyclopropenium bromides 9a–c under the action of HBr. The latter are likely obtained as a result of the HBr addition to the triple bond of (alk-1-ynyl)cyclopropenium bromides 8a–c initially formed in the reaction.This fact is confirmed by obtaining (2-bromo- 3,3-dimethylbut-1-enyl)diphenylcyclopropenium cation 11 from (3,3-dimethylbut-1-ynyl)diphenylcyclopropenium cation 10 in nearly quantitative yield (according to NMR data) under the treatment of a solution of cyclopropenium perchlorate 7a in CD3CN with HBr (Scheme 2). In the reaction mixtures formed both by the interaction of 4,4-dimethyl-1,1-dichloropent-2-yne 1a with ButOK in the presence of diphenylacetylene and under the treatment of (3,3- dimethylbut-1-ynyl)diphenylcyclopropenium perchlorate 7a with ButOK, identical products were detected.According to the 1H and 13C NMR spectrometry data, these products were identified as isomeric ethers 5a and 6a.This fact suggests that the above reactions proceed via the intermediate formation of ethers 5 and 6. We have also found that in the reactions of perchlorates 7a,b with MeONa in methanol at about –20 °C mixtures of corresponding isomeric cyclopropenic ethers 12a,b and 13a,b§ are formed with 58–67% yields (Scheme 3). Note that the 13C NMR signals due to b-carbon atoms at the § For a mixture of 12a and 13a (12a:13a ratio 1:1.3): overall yield 67% from perchlorate 7a. 1H NMR, d: for 12a, 1.27 (s, 9H, But), 3.52 (s, 3H, MeO), 7.2–7.6 (m, 6H, meta- and para-H, 2Ph), 7.83 (br. d, 4H, ortho- H, 2Ph, J 7.8 Hz); for 13a, 1.34 (s, 9H, But), 3.33 (s, 3H, MeO), 7.2–7.6 (m, 10H, 2Ph). 13C NMR, d: for 12a and 13a, 27.2 and 28.6 (CMe3), 29.9 and 30.5 (CMe3), 53.2 and 54.6 (MeO), 65.4, 66.8, 76.3, 90.3, 106.4 and 114.6 (COMe, CºC), 114.5, 120.6, 124.2, 126.4, 128.9 and 141.4 (C=C, ipso-C, Ph), 125.8, 126.6, 128.2, 129.0, 129.1, 129.5, 129.7 and 130.0 (Ph). IR (thin film, n/cm–1): 2210 (CºC).For a mixture of 12b and 13b (12b:13b ratio 1:1.2): overall yield 58% from perchlorate 7b. 1H NMR, d: for 12b, 3.63 (s, 3H, MeO), 7.2–7.7 (m, 11H, 3Ph), 7.89 (br.d, 4H, ortho-H, 2PhC=, J 7.8 Hz); for 13b, 3.39 (s, 3H, MeO), 7.2–7.7 (m, 15H, 3Ph). 13C NMR, d: for 12b and 13b, 53.3 and 55.1 (MeO), 67.2, 77.0, 81.4, 87.8, 104.1 and 105.3 (COMe, CºC), 120.1, 121.9, 122.8, 126.4, 126.9, 128.5 and 141.2 (C=C, ipso-C, Ph), 125.9, 126.3, 126.8, 128.1, 128.3, 128.4, 128.6, 129.1, 129.2, 129.3, 129.5, 129.7, 130.0, 130.5, 131.4, 131.6 (Ph). IR (thin film, n/cm–1): 2198, 2214 (CºC).triple bond of perchlorates 7a–c are downfield (126–138 ppm) with respect to the corresponding signals of other acetylenes, for example, (alk-1-ynyl)halocyclopropanes (75–95 ppm).4–5 These results suggest the conjugation between the triple bond and the cyclopropenium cation in salts 7a–c. This work was supported in part by the Russian Foundation for Basic Research (grant nos. 96-03-32907a and 96-15-97323). References 1 K. N. Shavrin, I. V. Krylova, I. E. Dolgy and O. M. Nefedov, Izv. Akad. Nauk, Ser. Khim., 1992, 1128 (Bull. Russ. Acad. Sci., Div. Chem. Sci., 1992, 41, 885). 2 K. N. Shavrin, I. V. Krylova, I. B. Shvedova, G. P. Okonnishnikova, I. E. Dolgy and O. M. Nefedov, J. Chem. Soc., Perkin Trans. 2, 1991, 1875. 3 K. N. Shavrin, I. B. Shvedova and O. M. Nefedov, Izv. Akad. Nauk, Ser. Khim., 1991, 2559 (Bull. Acad. Sci. USSR, Div. Chem. Sci., 1991, 40, 2235). 4 K. N. Shavrin, V. D. Gvozdev and O. M. Nefedov, Mendeleev Commun., 1997, 144. 5 K. N. Shavrin, V. D. Gvozdev and O. M. Nefedov, Izv. Akad. Nauk, Ser. Khim., 1997, 2079 (Russ. Chem. Bull., 1997, 46, 1973). 6 R. Breslow and H. W. Chang, J. Am. Chem. Soc., 1961, 83, 2367. Scheme 2 Ph Ph But Ph Ph H Br But HBr, CD3CN 10 11 Ph Ph R ClO4 7a,b i Ph Ph MeO R R Ph MeO Ph 12a,b 13a,b a R = But b R = Ph Scheme 3 Reagents and conditions: i, MeONa, MeOH, –20 °C. Received: 5th February 1999; Com. 99/1439

ISSN:0959-9436     

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) Reaction of 2,2-dibromotricyclo[7.1.01,9.01,3]decane with methyllithium: synthesis of bicyclo[7.1.0]decadiene-1,2 and dibromotriangulane rearrangement Elena B. Averina, Tamara S. Kuznetsova,* Alexey N. Zefirov, Alexey E. Koposov, Yuri K. Grishin and Nikolai S. Zefirov* Department of Chemistry, M. V. Lomonosov Moscow State University, 119899 Moscow, Russian Federation.Fax: +7 095 939 0290; e-mail: kuzn@org.chem.msu.su Reaction of 2,2-dibromotricyclo[7.1.01,9.01,3]decane with methyllithium gives strained cyclic allene 1 containing an ethenylidenecyclopropane unit in a nine-membered ring and dimer 6 resulting from a dibromotriangulane rearrangement. Recently we suggested a synthetic approach to highly energetic branched triangulanes,1 which consists in the synthesis of corresponding allenes followed by cyclopropanation of the double bonds.2 We expected that the introduction of an allene fragment into a middle-sized ring will permit us to use these cyclic allenes as starting compounds for the synthesis of peripherally cyclopropanated structures (cyclosubstituted triangulanes2,3).However, only few examples of allenes incorporated into a nine-membered ring are known up to now.4 Moreover, such cyclic allenes containing a cyclopropane unit connected to a double bond are still not known. This work concerns the synthesis of bicyclo[7.1.0]deca-1,2-diene 1 which is the first example of a strained cyclic alkenylidenecyclopropane. We used the standard synthetic procedure for generating allene fragments, which consists in [1 + 2]-cycloaddition of dibromocarbene to a corresponding olefin followed by the treatment of the obtained dibromocyclopropane with methyllithium in ether.5 Thus, we have synthesised previously unknown dibromide 2 (77% yield) by the treatment of bicyclo- [6.1.0]non-1-ene 36 with bromoform and ButOK in hexane.The reaction of dibromide 2 with methyllithium (obtained from lithium and MeI in diethyl ether) was performed at –40 °C and 0 to –5 °C.A mixture of four products (1, the main product, and 4–6) was obtained in both cases. The yield of allene 1 increased by 10% (up to 30%) as the temperature increased from 0 to –5 °C. Compounds 1, 4–6 extracted from the reaction mixture. Allene 1 was distilled to a bulb cooled with liquid nitrogen at 2×10–3 Torr without heating.The residue was dissolved in ether, the solution was placed in a refrigerator (ca. –20 °C) and the obtained crystalline precipitate of 6 was collected on a filter. Compounds 4 and 5 were obtained from the remaining solution by preparative GLC.† All of the obtained compounds were characterised by 1H and 13C NMR and mass spectrometry.Analyses of the NMR spectra and spectra–structure correlations were made by double resonance techniques and two-dimensional homonuclear (COSY H–H) and heteronuclear (COSY C–H) correlations.‡ Interpretation of the 1H and 13C NMR spectra of triangulanes 1–3 was based on the characteristic difference of the geminal coupling constants 2JHH (and 1JCH for compound 2) of the three- and eight-membered rings. The existence of a cumulene unit in substance 1 was supported by 13C NMR signals with chemical shifts typical of allenes7 at 85.8 and 91.7 ppm for † Reaction of dibromide 2 with MeLi.To a magnetically stirred solution of 3.5 g (0.0119 mol) of dibromide 2 in 20 ml of dried diethyl ether under argon 13.8 ml of 1.45 M MeLi (obtained from lithium and MeI) in diethyl ether was added dropwise during 40 min at 0 to –5 °C.The reaction mixture was stirred for 2 h and then quenched with water. The organic layer was separated, washed with water and dried with MgSO4. The solvent was evaporated under reduced pressure (1 Torr) into a trap cooled at –80 °C. The ‘bulb-to-bulb’ distillation of the residue at 2×10–2 Torr into a trap cooled with liquid N2 gave ~0.4 g of allene 1 (~30%). The residue was dissolved in ether and kept at –18 °C during a week.Obtained white solid compound 6 (0.020 g, ~3%) was filtered off. GLC of the residue gave fraction I of 0.20 g (~10%) of monobromide 4 and fraction II of 0.10 g (~10%) of olefin 5. ‡ The 1H (400 MHz) and 13C (100 MHz) NMR spectra were recorded on a Varian VXR-400 spectrometer in CDCl3, TMS as a standard.Mass spectra were obtained on Varian MAT 311A and 1321A spectrometers. GLC analyses and separations were performed using silicon E-301 (15% on Inerton AW). Bicyclo[7.1.0]deca-1,2-diene 1. 1H NMR, d: 0.85 (m, 1H), 1.17 (m, 1H), 1.31 (ddd, 1H, 2-H, 2J 7.1 Hz, 5J 3.2 Hz, 3J 4.8 Hz), 1.52–1.74 (m, 5H), 1.57 (m, 1H, 2'-H), 1.90 (m, 1H, 6-H, 2J 16.0 Hz), 1.93 (m, 1H), 2.07 (m, 1H, 1-H), 2.29 (m, 1H, 6'-H, 2J 16.0 Hz), 5.21 (m, 1H, 5-H). 13C NMR, d: 12.75 (C-2), 19.68 (C-1), 24.19, 26.56, 26.80 and 27.19 (C-7 through C-10), 30.67 (C-6), 85.79 (C-3), 91.66 (C-5), 193.15 (C-4). MS, m/z (%): 134 (3) [M]+, 133 (3) [M – 1]+, 119 (16), 105 (33), 106 (16), 93 (19), 92 (26), 91 (100), 79 (38), 78 (30), 77 (45), 67 (17), 66 (10), 65 (22), 51 (18), 41 (29).IR, n/cm–1: 1950 (C=C=C). 2,2-Dibromotricyclo[7.1.0.04,3]decane 2. 1H NMR, d: 0.95 (dd, 1H, 2'-H, 2J 4.8 Hz, 3J 6.0 Hz), 1.02 (m, 1H, 7-H), 1.19 (dd, 1H, 2-H, 2J 4.8 Hz, 3J 8.8 Hz), 1.30 (m, 1H, 8-H), 1.32 (m, 1H, 9-H), 1.43 (m, 1H, 7'-H), 1.56 (m, 1H, 8'-H), 1.59 (m, 1H, 10-H), 1.60 (m, 1H, 9'-H), 1.63 (m, 1H, 1-H), 1.71 (m, 1H, 6-H, 2J 14.6 Hz, 3J 8.0 Hz), 1.86 (m, 1H, 6'-H), 2.08 (m, 1H, 10'-H), 2.08 (m, 1H, 5-H). 13C NMR, d: 15.69 (C-2, J 163 Hz), 19.75 (C-7, J 125 Hz), 22.82 (C-1, J 163 Hz), 23.26 (C-9, J 127 Hz), 27.47 (C-6, J 128 Hz), 28.38 (C-10, J 128 Hz), 30.70 (C-8, J 127 Hz), 33.48 (C-3), 35.46 (C-5, J 162 Hz), 40.72 (C-4). Found (%): C, 40.85; H, 4.80. Calc. for C10H14Br2 (%): C, 41.39; H, 5.32. 2-Methyl-2-bromotricyclo[7.1.0.01,3]decane 4. 1H NMR, d: 0.63 (dd, 1H, 2'-H, 2J 4.3 Hz, 3J 5.4 Hz), 1.00 (dd, 1H, 2-H, 1J 4.3 Hz, 3J 8.6 Hz), 1.31 (m, 1H, 1-H), 1.33 (m, 1H), 1.40–1.75 (m, 7H), 1.88 (dm, 1H), 1.75 (s, 3H, Me), 2.03 (m, 1H, 6-H). 13C NMR, d: 9.77 (C-2), 18.78 (C-1), 19.26 (C-7), 23.60 (C-9), 26.65 (C-6), 27.94 (C-8), 29.85 (C-10), 27.73 (Me), 28.66 (C-3), 28.80 (C-5), 44.79 (C-4). MS, m/z (%): 149 (39) [M – Br]+, 135 (4), 133 (8), 121 (12), 119 (11), 107 (47), 105 (30), 95 (46), 93 (42), 91 (62), 67 (70), 55 (35), 53 (32), 41 (42), 39 (29). 2,3-Dimethylnona-1,3-diene 5. 1H NMR, d: 1.40 (br. m, 4H, 5-H), 1.56 (m, 2H, 6-H), 1.75 (d, 6H, 1-H, 4J 1.5 Hz), 1.98 (m, 4H, 4-H), 5.31 (tq, 2H, 3-H, 3J 8.5 Hz, 4J 1.5 Hz). 13C NMR, d: 21.57 (C-1), 27.07 and 29.59 (C-4 and C-5), 29.90 (C-6), 125.90 (C-3), 138.00 (C-2).MS, m/z (%): 150 (49) [M]+, 135 (38), 121 (28), 107 (77), 93 (100), 91 (63), 79 (91), 77 (48), 67 (77), 55 (45), 53 (46), 51 (27), 41 (96), 39 (92), 29 (38), 27 (67). 9,9'-Diiodo-2,2'-bis(bicyclo[6.1.1]dec-9-ene) 6. 1H NMR, d: 0.96– 1.21 (m, 6H), 1.50–1.86 (m, 12H), 1.93 (m, 2H), 2.02 (m, 2H), 2.57 (d, 2H, 2-H, 2J 11.0 Hz), 2.70 (dd, 2H, 2'-H, 2J 11.0 Hz, 3J 4.4 Hz), 3.16 (br.t, 2H, 1-H, 3J 4.4 Hz, 3J 4.5 Hz). 13C NMR, d: 27.09, 27.74, 29.15, 29.99, 33.82 (C-6 through C-10), 37.42 (C-2), 45.13 (C-1), 46.91 (C-5), 92.16 (C-3), 157.90 (C-4). Br Br CHBr3 ButOK DMSO Me Br Me Me I I MeLi diethyl ether 3 2, 77% 1, 30% 4, ~10% 5, ~10% 6, ~3% 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 1 2 3 4 5 6 7 8 9 10Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) edge carbon atoms and 193.1 ppm for the central atom. The long-range coupling between the terminal allene proton and one of the methylene protons (5JHH 3.2 Hz) point at the direct connection of this unit with the three-membered ring. The structure of the diene unit of compound 5 (the adjacent position of the two methyl groups at inner carbon atoms of the diene unit) was based on the spin–spin coupling data.The structure of dimer 6 was unequivocally established by X-ray crystal structure analysis.§ The obtained results are remarkable. First, we have synthesised strained cyclic allene 1 having cyclopropane unit directly connected to an allene unit. Second, the isolation of by-products 4, 5 and, especially, 6 is important for a general understanding of the process.The intermediate formation of monobromolithium species in the reaction of dibromocyclopropanes with methyllithium is well documented.4 However, the formation of by-products of the type 4 and 5 was not observed and hence was unexpected. It seems that the formation of monobromide 4 resulted from the methylation of a lithiumcarbenoid intermediate in the presence of methyl bromide or methyl iodide in the reaction mixture.4(e) A reasonable mechanism for the formation of olefin 5 is the sequence of bromine–lithium exchange on 4 followed by a ringopening rearrangement, subsequent protonation and electrocyclic ring opening of the ring-annelated cyclobutene.8 The isolation of the dimeric diiodide is especially remarkable. Previously we have described the unique rearrangement7 of triangulane dibromides 7 in the presence of methyllithium to give corresponding cyclobutene dibromides 8 as primary products in accordance with the scheme While the isomeric dibromides can be isolated, they undergo further transformation in the presence of an excess of MeLi to give dimeric products 9 in the case of R' = H.It is of interest that the presence of iodide anions in the reaction mixture (from § Crystal data for 6 were obtained by Dr. A. E. Lysov and Dr. K. A. Potekhin (Vladimir, Russian Federation); the detailed results will be published elsewhere. the reaction of MeI with Li) leads to formation of iodides 9b. However, the detailed mechanism of this rearrangement still remains speculative.This work was supported by the Russian Foundation for Basic Research (grant no. 98-03-32876a). References 1 (a) N. S. Zefirov, S. I. Kozhushkov, T. S. Kuznetsova, O. V. Kokoreva, K. A. Lukin, B. I. Ugrak and S. S. Tratch, J. Am. Chem. Soc., 1990, 112, 7702; (b) T. S. Kuznetsova, A. N. Zefirov and N. S. Zefirov, Izv. Akad. Nauk, Ser. Khim., 1995, 1613 (Russ.Chem. Bull., 1995, 44, 1543). 2 N. S. Zefirov, T. S. Kuznetsova, O. V. Eremenko, O. V. Kokoreva, G. V. Zatonsky and B. I. Ugrak, J. Org. Chem., 1994, 59, 4089. 3 T. S. Kuznetsova, O. V. Eremenko, O. V. Kokoreva, E. B. Averina, A. N. Zefirov and N. S. Zefirov, Zh. Org. Khim., 1997, 33, 916 (Russ. J. Org. Chem., 1997, 33, 849). 4 (a) L. Skattebol and S. Salomon, Org.Synth., 1969, 49, 35; (b) M. S. Baird and C. B. Reese, Tetrahedron, 1976, 32, 2153; (c) L. Skattebol, Acta Chem. Scand., 1963, 17, 1683; (d) D. E. Minter, Y. J. Fonken and T. T. Cook, Tetrahedron Lett., 1979, 711; (e) H. J. J. Loozen, W. A. Castenmiller, E. J. M. Buter and H. M. Buck, J. Org. Chem., 1976, 41, 2965. 5 H. F. Schuster and G. M. Coppola, Allenes in Organic Synthesis, Wiley, New York, 1984. 6 (a) C. L. Osborn, T. C. Shields, B. A. Shoulders, J. F. Crause, H. V. Cortes and P. D. Gardner, J. Am. Chem. Soc., 1965, 87, 3158; (b) T. J. Stierman and R. P. Johnson, J. Am. Chem. Soc., 1985, 107, 3971. 7 K. A. Lukin, N. S. Zefirov, D. S. Yufit and Yu. T. Struchkov, Tetrahedron, 1992, 48, 9977. 8 A. de Mejere and S. I. Kozhushkov, in Advances in Strain in Organic Chemistry, ed. B. Halton, JAI Press, Greenwich, 1995, vol. 4, p. 225. Me Br 4 MeLi Me Li Li Me H+ Me Me 5 R' R' Br Br R R MeLi ( X – ) X R' R' Br R R X R R R' R' X R R R' R' 7 8 9a X = Br 9b X = I Received: 24th November 1998; Com. 98/1405 (8/09468C)

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Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) First 1H NMR observation of chair–boat conformers in bispidinone system. Molecular structure of 3,7-diisopropyl-1,5-diphenyl-3,7-diazabicyclo- [3.3.1]nonane-9-one Sergey Z. Vatsadze,*a,b Dmitry P. Krut’ko,b Nikolai V. Zyk,b Nikolai S. Zefirov,b Andrei V. Churakovc and Judith A. Howardc a Department of Chemistry, University of Nottingham, Nottingham NG7 2RD, UK b Department of Chemistry, M.V. Lomonosov Moscow State University, 119899 Moscow, Russian Federation. Fax: +7 095 939 0290; e-mail: szv@org.chem.msu.su c Department of Chemistry, University of Durham, Durham DH1 3LE, UK In the solid state bispidinone 4 exists in a CB conformation and in solution undergoes rapid degenerate interconversion CB BC as revealed by variable temperature 1H and 13C NMR studies .The conformational analysis of 3,7-diazabicyclo[3.3.1]nonanes (bispidines) is of considerable interest both from the theoretical viewpoint1 and due to their biological activiy.2 Recently, bispidines were recognised as perspective pre-organised ligands towards transition metals.3,4 They are also of particular interest due to transformations of their chiral organolithium derivatives.5 All complexes so far studied by X-ray diffraction show the bispidine’s bicyclic backbone to exist in a double-chair (CC) conformation that resembles the adamantane structure and may cause specific complexation properties of these ligands.3,6 The same solid state conformation is found in 1,5-diphenylbispidin- 9-ones 1 (Scheme 1) (as well as for 5,7-diphenyl-1,3-diazaadamantan- 6-one 27) which have a carbonyl or nitroso function adjacent to the nitrogen atoms.8,9 In contrast, in the solid state 3,7-dialkyl- and 3,7-ditosylsubstituted derivatives 3 present a chair–boat (CB) conformation.4,9,10 Moreover, CB conformations exist in bispidine-based macrocyclic crown ethers.11,12 Whereas the conformational effects in 1,5-diphenylbispidinones in the solid state have been extensively studied by X-ray diffraction techniques, there is little work devoted to their conformational behaviour in solution.In the mid 1970’s, dipole moment investigations of 1,5-diphenyl derivatives led Scheiber and Nador to the assumption that in solution these compounds undergo a degenerate chair–boat boat–chair (CB BC) interconversion13 (Scheme 1).Studying variable temperature 13C NMR spectra of 3 (R = Me, CH2Ph, Ts) revealed the same conclusion.1,9,14 In the case where R = Me different values of the free activation energy DG� (9.7 kcal mol –1 and 8.7 kcal mol–1 in refs. 14 and 1, respectively) were reported. The same parameter for R = CH2Ph analogue is found to be 8.4 kcal mol–1.9 As a consequence of the rapid equilibria 3a 3b at room temperature the 1H NMR spectra of the ring protons present an AB-system like quartet within the ranges 3.9–3.4 and 2.9–3.4 ppm. Recently, Black et al.12 examined the dynamic proton NMR behaviour of macrocycle 3 [R + R = CH2(CH2OCH2)3CH2] and reported that the high-field doublet assigned to the ‘axial’ protons of a bispidinone ring broadened on cooling and separated into a pair of doublets.The corresponding DG� value is found to be 9.1 kcal mol–1. We have previously described the possible criteria for determining the conformations of 1,5-diphenylbispidinones in solution.15 Chemical shifts of carbonyl carbons as well as carbons at ipso-position in phenyl rings for CC conformation 1 appear to lie at higher fields as compared to those of type 3. Thus, compounds 3 [R = Me, allyl, CH2Ph, CH(Ph)Me, CH2CH2CN, CH2CO2Et] have carbonyl carbon chemical shifts at 210–212 ppm and those of ipso-carbons at 142–144 ppm while for 1 (R = Ac) and 2 these values are 204–205 and 134–135 ppm, respectively.On this basis, we also suggest the conformational type 3 for several new bispidinones (R = Et, Pri, CH2CH2OMe, 2-furylmethyl, CH2CH2CH2OEt). Here we report that our rationale is unambiguously confirmed by dynamic 1H and 13C NMR spectroscopic studies and crystal structure investigation in the case of N,N'-diisopropylsubstituted diphenylbispidinone 4.† In the 13C NMR spectra of 4 below –74 °C, the peak that at room temperature corresponds to the resonances of four methylene carbons splits into a pair of broadened signals of equal intensity (labelled Ca and Cb, see below), which are separated by 6.6 ppm at –100 °C.The signal related to the carbons of the isopropyl methyl groups also splits into two peaks at 17.56 and 17.04 ppm, while that related to the methine carbons is broadened. At the same time, the Ph–C–C(O)–C–Ph moiety demonstrates sharp resonance signals within the whole temperature range studied.All these facts are in complete accordance with an assumption of a degenerate CB BC † The sealed evacuated degassed sample of 0.17 M concentration in absolute CD2Cl2 was used. All measurements were performed on a Varian VXR-400 spectrometer. The temperature calibrations were carried out by conventional techniques (with a standard methanol sample). 4: 1HNMR (400 MHz, CD2Cl2, 25 °C) d: 7.43–7.23 (m, 10H, Ph), 3.57 (d, 4H, CH2, 2J 10.4 Hz), 3.21 (d, 4H, CH2, 2J 10.4 Hz), 3.06 (sept, 2H, CH, 3J 6.4 Hz), 1.08 (d, 6H, Me, 3J 6.4 Hz). 13C NMR (100 MHz, CD2Cl2, 25 °C) d: 212.14 [C(9)], 144.76 (Cipso), 128.15 (Cmeta), 127.30 (Cortho), 126.72 (Cpara), 60.92 (CH2), 55.01 [C(1) and C(5)], 54.67 (CH), 18.53 (Me). N N Ph Ph R R 1 N N Ph Ph 2 O O N N Ph Ph R R 3a O N N Ph Ph R R 3b O Scheme 1 N N Ph Ph Pri Pri O Ha Hd Hc Hb Ca Cb 56.1 ppm 2.93 ppm 3.36 ppm 3.72 ppm 62.7 ppm 3.18 ppm Scheme 2Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) interconversion taking place. Slowing of this process at low temperatures makes it possible to observe individual signals of chair and boat conformations.Equally dramatic changes are observed in the 1H NMR spectrum when the temperature is lowered. At –100 °C the methyl and methine groups of the isopropyl substituents give two pairs of broadened signals at 1.13 and 0.99 ppm, and at 3.13 and 2.93 ppm, respectively, whilst four skeleton protons Ha, Hb, Hc and Hd are represented by four signals corresponding to two AB systems (Figure 1).By means of selective homo- and heteronuclear double resonance experiments, protons Ha and Hc were found to be part of one spin system that also includes Ca, while the signals of Hb, Hd and Cb correspond to another. The obtained data allow us to assume tentatively that Ha, Hc and Ca belong to a chair ring while Hb, Hd and Cb are assigned to a boat ring.Indeed, the literature data prove that the lowfield signals in the 13C NMR spectra of the natural sparteinic alkaloids correspond to the rings of the boat conformation.16 It was also established that in the 1H NMR spectrum of sparteine, which exists in a CB conformation, the signal of the equatorial proton of the ring in the chair conformation is downfield shifted as compared to that in the boat conformation.17 The nitrogen lone pair in quinuclidines and related systems is also known to have a shielding effect on the adjacent axial proton.17 Thus, the signals in the 13C and 1H NMR spectra of 4 at –100 °C should be preferably assigned as shown on Scheme 2.The consecutive changes in the 1H NMR spectrum upon cooling or heating present an additional argument for the given assignment (see Figure 1).It is clearly seen that the signals Ha–Hb and Hc–Hd collapse in pairs. It is the very same picture that should be expected for the simultaneous inversion of both of the six-membered rings of 3 (see Scheme 1) in which the axial chair-ring protons exchange with the equatorial protons of the boat-ring and vice versa. From this point of view, it becomes apparent that the AB-system observed in the roomtemperature 1H NMR spectra of 1,5-diphenylbispidinones is derived from the superposition of four signals, and it is incorrect to assign any of observable doublets to the ‘axial’ or ‘equatorial’ protons. The free activation energy of interconversion of 4 was calculated by the CT method on the basis of the measured coalescence temperatures of the signals of the skeleton carbons and hydrogens.The derived DG� values are in close agreement (Table 1). X-Ray analysis of compound 4 confirmed the CB conformation in the solid state (Figure 2).‡ The asymmetric unit contains 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 25.0 °C –57.5 °C –73.5 °C –79.0 °C –84.0 °C –95.0 °C –100.0 °C 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 Figure 1 VT 1H NMR spectra of 4 (aliphatic region).d/ppm Ha Hb Hc Hd C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(21) C(22) C(23) C(24) C(25) C(26) N(2) O N(1) C(31) C(32) C(33) C(34) C(35) C(36) C(21') C(22') C(23') C(24') C(25') C(26') C(8') C(11') C(10') C(9') C(12') C(13') C(1') O' C(7') N(1') N(2') C(4') C(3') C(6') C(5') C(2') C(31') C(32') C(33') C(34') C(35') C(36') Figure 2 Molecular structure of 4.Selected bond lengths (Å): O–C(1) 1.212(5), N(1)–C(7) 1.457(6), N(1)–C(2) 1.465(6), N(1)–C(8) 1.487(6), N(2)–C(5) 1.460(6), N(2)–C(4) 1.463(6), N(2)–C(9) 1.485(6), O'–C(1') 1.220(5), N(1')–C(2') 1.453(6), N(1')–C(7') 1.469(6), N(1')–C(8') 1.493(6), N(2')–C(5') 1.454(6), N(2')–C(4') 1.455(6), N(2')–C(9') 1.485(6); selected bond angles (°): C(7)–N(1)–C(2) 110.1(4), C(7)–N(1)–C(8) 112.9(4), C(2)–N(1)–C(8) 113.9(4), C(5)–N(2)–C(4) 111.6(4), C(5)–N(2)–C(9) 112.3(4), C(4)–N(2)–C(9) 115.1(4), C(2')–N(1')–C(7') 110.4(4), C(2')–N(1')–C(8') 113.5(4), C(7')– N(1')–C(8') 114.4(4), C(5')–N(2')–C(4') 111.8(4), C(5')–N(2')–C(9') 114.6(4), C(4')–N(2')–C(9') 112.6(4).Table 1 Coalescence temperatures (CT), Dn values and calculated DG� for 4. Spectrum Nuclei CT/°C Dn (–100 °C)/ Hz DG�/ kcal mol–1 13C Ca and Cb –74.5±1.5 659 8.6±0.1 1H Ha and Hb –83.5±1.0 145 8.7±0.1Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) two independent molecules with very close geometrical parameters for a bispidinone skeleton.However, the conformations of N–CHMe2 groups are not the same. The differences between relative C–C–N–C angles range within 8.1–11.4°. Both nitrogen atoms are pyramidal [C–N–C angles are within 110.1(4)– 115.4(4)°]. It is of interest that N–C(isopropyl) bonds [1.485(6)– 1.493(6) Å] are systematically longer than N–C(skeleton) bonds [1.453(6)–1.469(6) Å].A.V.C. thanks The Royal Society and The University of Durham for finacial support. S.Z.V. and N.V.Z. acknowledge the financial support of the work by the Russian Foundation for Basic Research (grant no. 99-3-33034). References 1 N.S. Zefirov and V. A. Palyulin, Topics in Stereochemistry, 1991, 20, 171. 2 M. J. Fernandez, R. M. Huertas, E. Galvez, A. Orjales, A. Berisa, L. Labeaga, A. G. Garcia, G. Uceda, J. Servercarrio and M. Martinezripoll, J. Mol. Struct., 1995, 372, 203. 3 (a) P. Comba, B. Nuber and A. Ramlow, J. Chem. Soc., Dalton Trans., 1997, 347; (b) G. D. Hosken, C. C. Allan, J. C. A. Boeyens and R.D. Hancock, J. Chem. Soc., Dalton Trans., 1995, 3705; (c) S. Z. Vatsadze, N. V. Zyk, R. D. Rakhimov, K. P. Butin and N. S. Zefirov, Izv. Akad. Nauk, Ser. Khim., 1995, 456 (Russ. Chem. Bull., 1995, 44, 440); (d) G. D. Hosken and R. D. Hancock, J. Chem Soc., Chem. Commun., 1994, 1363. 4 D. St. C. Black, G. B. Deacon and M. Rose, Tetrahedron, 1995, 51, 2055. 5 D. J. Gallagher, S.D. Wu, N. A. Nikolic and P. Beak, J. Org. Chem., 1995, 60, 8148. 6 (a) A. Gogoll, H. Grennberg and A. Axen, Organometallics, 1997, 16, 1167; (b) S. Z. Vatsadze, V. K. Belsky, S. E. Sosonyuk, N. V. Zyk and N. S. Zefirov, Khim. Geterotsikl. Soedin., 1997, 356 [Chem. Heterocycl. Compd. (Engl. Transl.), 1997, 300]; (c) S. Z. Vatsadze, S. E. Sosonyuk, N. V. Zyk, K. A. Potekhin, O. I.Levina, Yu. T. Struchkov and N. S. Zefirov, Khim. Geterotsikl. Soedin., 1996, 770 [Chem. Heterocycl. Compd. (Engl. Transl.), 1996, 461]. 7 S. A. Pisarev, A. I. Yanovskii, Yu. T. Struchkov, V. A. Palyulin and N. S. Zefirov, Vestn. Mosk. Univ., Ser. 2, Khim., 1996, 37, 485. 8 O. I. Levina, K. A. Potekhin, E. N. Kurkutova, Yu. T. Struchkov, I. I. Baskin, V. A. Palyulin and N. S. Zefirov, Dokl.Akad. Nauk SSSR, 1985, 281, 1367 (in Russian). ‡ The single crystal of 4 of approximate dimensions 0.2×0.2×0.1 mm was mounted in inert oil on the top of glass fibre and transferred to a cold nitrogen stream on a Siemens SMART CCD diffractometer. Crystal data: C25H32N2O, M = 376.53, monoclinic, a = 11.9515(2), b = 18.0538(4), c = 19.9549(1) Å, b = 91.678(1)° (refined from all collected reflections during data reduction18), V = 4226.18(12) Å3, space group P21/c, Z = 8, Dc = 1.184 g cm–3, F(000) = 1632, m(MoKa) = 0.072 mm–1.Total of 25403 reflections (7445 unique, Rint = 0.1965) were measured using graphite monochromated MoKa radiation (l = 0.71073 Å) at 100.0(2) K. Data were collected in the range 1.53 < q < 25.00 (–15 £ h £ 15, –23 £ k £ 13, –23 £ l £ 25); w scan mode with a step of 0.3° (40 s per step) was used.The Siemens SAINT software was applied for data reduction.18 Absorption correction was not performed since it did not lead to any improvement of the data.19 7078 reflections with I > –3s(I) were used in further calculations. The structure was solved by direct methods20 and refined by full matrix least-squares on F2 (ref. 21) with anisotropic thermal parameters for all non-hydrogen atoms. All H atoms were found from difference Fourier syntheses and refined in an isotropic approximation [H(2B), H(26) and H(22') with fixed Uiso = 0.03 Å2]. The weighting scheme was w–1 = s2(F2) + 9.1459P, where P = (2Fc 2 + Fo 2)/3. The final residuals were: R1 = 0.0892, wR2 = 0.01473 for 3936 reflections with I > 2s(I) and 0.1955, 0.2227 for all data and 759 parameters. GOOF = 1.143, maximum shift/e.s.d.= 0.000, maximum Dr = 0.335 e Å–3. Atomic coordinates, bond lenghts, bond angles and thermal parameters have been deposited at Cambridge Crystallographic Data Centre (CCDC). For details, see ‘Notice to Authors’, Mendeleev Commun., Issue 1, 1999. Any request to the CCDC for data should quote the full literature citation and the reference number 1135/46. 9 P.H. McCabe, N. J. Milne and G. A. Slim, J. Chem. Soc., Chem. Commun., 1985, 625. 10 (a) For a review before 1991 see ref. 1; (b) S. V. Chemodanova, K. A. Potekhin, V. A. Palyulin, I. N. Shishkina, V. M. Demyanovich, Yu. T. Struchkov, V. V. Samoshin and N. S. Zefirov, Dokl. Ross. Akad. Nauk, 1992, 326, 847 [Dokl.Chem. (Engl. Transl.), 1992, 326, 236]; (c) S. Z. Vatsadze, S. E. Sosonyuk, N. V. Zyk, K. A. Potekhin, O. I. Levina, Yu. T. Struchkov and N. S. Zefirov, Dokl. Ross. Akad. Nauk, 1995, 341, 201 [Dokl. Chem. (Engl. Transl.), 1995, 341, 70]; (d) V. A. Palyulin, K. A. Potekhin, A. E. Lysov, S. V. Emets, S. V. Starovoitova, N. S. Zefirov and X. X. Schneider, Dokl. Ross. Akad.Nauk, 1996, 350, 353 [Dokl. Chem. (Engl. Transl.), 1996, 350, 41]. 11 (a) K. A. Potekhin, Yu. T. Struchkov, S. V. Chemodanova, V. A. Palyulin, V. V. Samoshin and N. S. Zefirov, Dokl. Ross. Akad. Nauk, 1992, 324, 339 [Dokl. Chem. (Engl. Transl.), 1992, 324, 100]; (b. Carcanague, C. B. Knobler and F. Diederich, J. Am. Chem. Soc., 1992, 114, 1515; (c) N. S. Zefirov, V. A. Palyulin, K. A. Potekhin, S. V. Starovoytova and Yu. T. Struchkov, Dokl. Ross. Akad. Nauk, 1996, 346, 342 [Dokl. Chem. (Engl. Transl.), 1996, 346, 15]. 12 D. St. C. Black, D. C. Craig, M. A. Norsham and M. Rose, Chem. Commun., 1996, 2093. 13 P. Scheiber and K. Nador, Acta Chim. Acad. Sci. Hung., 1975, 84, 193. 14 Y. Takeuchi, P. Scheiber and K. Takada, J. Chem. Soc., Chem. Commun., 1980, 403. 15 (a) S. Z. Vatsadze, 15th International Congress on Heterocyclic Chemistry, Taipei, 1995, pp. 2–164; (b) S. Z. Vatsadze, PhD Thesis, Moscow State University, Moscow, 1995. 16 F. Bohlmann and R. Zeisberg, Chem. Ber., 1975, 108, 1043. 17 F. Bohlmann, D. Schumann and C. Arndt, Tetrahedron Lett., 1965, 31, 2705. 18 SAINT Version 4.050, Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA, 1995. 19 G. M. Sheldrick, SHELXTL-Plus. Release 4.1, Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA, 1991. 20 G. M. Sheldrick, Acta Crystallogr. A, 1990, A46, 467. 21 G. M. Sheldrick, SHELXL-93. Program for the Refinement of Crystal Structures, University of Göttingen, Germany, 1993. Received: 12th January 1999; Com. 99/1424

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Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) 3,7-Diazabicyclo[3.3.1]nonane-2,6-diones: building of homo- and heterochiral crystals Remir G. Kostyanovsky,*a Konstantin A. Lyssenko,b Yuri I. El’natanov,a Oleg N. Krutius,a Irina A. Bronzova,a Yuri A. Strelenkoc and Vasily R. Kostyanovskya a N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow, Russian Federation.Fax: +7 095 938 2156; e-mail: kost@center.chph.ras.ru b A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 117813 Moscow, Russian Federation. Fax: +7 095 135 5085; e-mail: kostya@xray.ineos.ac.ru c N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow, Russian Federation. Fax: +7 095 135 5328; e-mail: strel@nmr.ioc.ac.ru A strategy in the synthesis of 1,5- or 3,7-unsubstituted derivatives of the title dilactams has been developed, and the parent 3,7-diazabicyclo[3.3.1]nonane-2,6-dione 4 was synthesised; the hydrogen bonding generated self-assembly as a heterochiral infinite diagonal zigzag tape was found in the crystal of 2 (space group P21/c) whereas a homochiral helical architecture was observed in 4 (space group P212121).In order to design molecules which are capable of the homochiral self-assembly to form crystalline conglomerates, bicyclic dilactams of the 3,7-diazabicylo[3.3.1]nonane-2,6-dione series were examined. It is anticipated a priori that the hydrogenbonded self-assembly will occur either in helical suprastructures, as in the case of chiral glycouril,1 or in heterochiral diagonal zigzag tapes, as in dilactam A of the bicyclo[3.3.0]- octane series2 (cf.ref. 3). Both of these opportunities can be realised. The only examples reported earlier are derivatives of 3,7- dialkyl-3,7-diazabicyclo[3.3.1]nonane-2,6-dione-1,5-dicarboxylic acids.4,5 To synthesise the target compounds, we have used a recently developed strategy for preparing similar dilactams A and B of the 3,7-diazabicyclo[3.3.0]octane-2,6-dione series2 (Scheme 1).Dilactam 1 was synthesised on the basis of tetraethyl propane- 1,1,3,3-tetracarboxylate6 using the method proposed by Knowles and co-authors4 with the new aminomethylating reagent 1,3,5- tris(4-methoxybenzyl)hexahydro-1,3,5-triazine.2 N-Deprotection of 1 with cerium ammonium nitrate (CAN)2 gives dilactam diester, and its subsequent deesterification leads to dilactam diacid 3.The latter was thermally decarboxylated to form parent dilactam 4. The opposite sequence of transformations has also been performed; it includes deesterification of 1 into 3,7-disubstituted dilactam diacid 5 and its decarboxylation into 3,7-disubstituted dilactam 6.The latter was a matter of particular interest because its analogue of the bicyclo[2.2.2]- octane series forms a conglomerate.7 However, product 6 was not found to be crystalline. All of the compounds were characterised by spectroscopic data† (Figure 1). The structures of 2 and 4 were confirmed by X-ray diffraction analysis‡ (Figures 2 and 3). Experimental values of the vicinal spin–spin coupling constants for 4 (cf. the data for bicyclo[3.3.1]nonane-2,6-diones8) are in agreement with those calculated by the general Karplus equation † Characteristics and spectroscopic data.NMR spectra were recorded on a Bruker WM-400 spectrometer [at 400.13 (1H) and 100.62 MHz (13C)], 1H NMR spectrum of 4 was recorded on a Bruker AM-300 spectrometer (at 300.13 MHz) and calculated by the CALM program (Resonance, Moscow, 1993). 1: yield 55%, mp 131–132 °C (Et2O–petroleum ether). 1HNMR (CDCl3) d: 1.24 (t, 6H, 2Me, 3J 7.5 Hz), 2.69 (t, 2H, 9-CH2, 4Jobs 1.2 Hz), 3.63 (dt, 2H, 4,8-CHb, 2J –12.8 Hz, 4Jobs 1.2 Hz), 3.77 (s, 6H, 2MeO), 3.80 (d, 2H, 4,8-CHa, 2J –12.8 Hz), 4.20 (m, 4H, 2CH2O, ABX3 spectrum), 4.52 (m, 4H, 3,7-NCH2, AB spectrum, Dn 26.0, 2J –14.6 Hz), 6.86 and 7.13 (d and d, 8H, 2C6H4, 3J 9.0 Hz). 13C NMR (CDCl3) d: 13.72 (qt, Me, 1J 127.2 Hz, 2J 2.9 Hz), 33.31 (br. t, 9-CH2, 1J 136.6 Hz), 49.73 (s, 1,5-C), 49.90 (t, 3,7-NCH2, 1J 138.8 Hz), 52.63 (br. tt, 4,8-CH2, 1J 145.3 Hz, 3J 4.4 Hz), 54.96 (q, MeO, 1J 143.8 Hz), 68.80 (tq, CH2O, 1J 148.2 Hz, 2J 4.4 Hz), 113.9 (dd, 3'-C, 1J 159.0 Hz, 2J 4.4 Hz), 127.6 (m, 1'-C), 129.05 (dm, 2'-C, 1J 157.6 Hz), 158.95 (br.s, 4'-C), 166.2 (br. s, CO2Et), 168.6 (br. s, 2,6-CO). 2: yield 49%, mp 203–205 °C (EtOH). 1H NMR (CDCl3) d: 1.29 (t, 6H, 2Me, 3J 7.0 Hz), 2.70 (t, 2H, 9-CH2, 4Jobs 1.2 Hz), 3.73 (ddt, 2H, 4,8-Hb, 2J –12.5 Hz, 3JHbe 4.3 Hz, 4Jbd'(d)obs 1.2 Hz), 3.84 (d, 2H, 4,8-Ha, 2Jab –12.5 Hz), 4.25 (q, 4H, 2CH2O, 3J 7.0 Hz). 13C NMR (CD3OD) d: 13.90 (qt, Me, 1J 127.2 Hz, 2J 2.9 Hz), 32.50 (tt, 9-CH2, 1J 137.0 Hz, 3J 7.0 Hz), 47.35 (tt, 4,8-CH2, 1J 147.0 Hz, 3J 5.2 Hz), 50.10 (s, 1,5-C), 62.75 (tq, CH2O, 1J 148.2 Hz, 2J 4.4 Hz), 170.0 and 170.2 (s and s, 2,6-CO and CO2). 3: yield 86%, mp 250–252 °C (decomp., from H2O). 1HNMR (CD3OD) d: 2.70 (s, 2H, 9-CH2), 3.65 (m, 4H, 4,8-CH2, AB spectrum, Dn 68.0, 2J –13.0 Hz). 4: yield 67.4%, mp 350 °C (MeOH). 1H NMR (CD3OD) d: 2.30 (m, 2H, dd', 2J –13.0 Hz, 3Jdc' = 3Jd'c = 3.72Hz, 3Jdc = 3Jd'c' = 2.57 Hz, 4Jdb' = = 4Jd'b = 2.02 Hz, 4Jda' = 4Jd'a = –0.33 Hz), 2.97 (m, 2H, cc', 3Jca = 3Jc'a' = = 5.02 Hz, 3Jcb = 3Jc'b' = 1.45 Hz, 4Jcc' –1.50 Hz), 3.52 (m, 2H, bb', 2Jba = 2Jb'a' = –13.04 Hz), 3.72 (m, 2H, aa'). 13C NMR (D2O) d: 22.0 (t, 9-CH2), 33.0 (d, 1,5-CH), 43.9 (t, 4,8-CH2), 173.6 (s, 2,6-CO). 5: yield 73%, mp 220 °C. 1H NMR (CD3OD) d: 2.70 (s, 2H, 9-CH2), 3.70 (m, 4H, 4,8-CH2, AB spectrum, Dn 60.0, 2J –12.7 Hz), 3.78 (s, 6H, 2MeO), 4.50 (m, 4H, 3,7-NCH2, AB spectrum, Dn 76.0, 2J –14.3 Hz), 6.87 and 7.12 (d and d, 8H, 2C6H4, 3J 8.5 Hz), 7.9 (s, 2H, 2CO2H). 6: yield 16%, viscous oil. 1H NMR (CDCl3) d: 2.09 (t, 2H, 9-CH2, 3J 3.0 Hz), 2.91 (dtd, 2H, 1,5-CH, 3Jac 4.7 Hz, 3Jcd 3.0 Hz, 3Jbc 1.0 Hz), 3.40 (dd, 2H, 4,8-HaHa', 2Jab –12.1 Hz, 3Jac 4.7 Hz), 3.48 (dd, 2H, 4,8- HbHb', 2Jab –12.1 Hz, 3Jbc 1.0 Hz), 3.80 (s, 6H, 2MeO), 4.50 (m, 4H, 3,7-NCH2, AB spectrum, Dn 120.0, 2J –14.1 Hz), 6.82 and 7.11 (d and d, 8H, 2C6H4, 3J 8.7 Hz). 13C NMR (CDCl3) d: 25.44 (t, 9-C, 1J 133.7 Hz), 36.90 (d, 1,5-C, 1J 137.5 Hz), 49.10 (tt, 3,7-NCH2, 1J 138.6 Hz, 3J 4.0 Hz), 51.10 (t, 4,8-CH2, 1J 141.3 Hz), 55.10 (q, MeO, 1J 143.7 Hz), 113.9 (dd, 3'-C, 1J 160.2 Hz, 2J 5.0 Hz), 128.16 (s, 1'-C), 129.0 (ddt, 2'-C, 1J 158.0 Hz, 2J 7.0 Hz, 3J 3.5 Hz), 158.9 (s, 4'-C), 169.8 (s, 2,6-CO). 3.8 3.7 3.6 3.5 3.1 3.0 2.9 2.4 2.3 d/ppm Figure 1 1H NMR spectra of 4: (a) an experimental spectrum in CD3OD and (b) a spectrum calculated by CALM. (a) (b)Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) (3JHH)9 and by an equation for norbornanes (3JCH)10 from the MM2 geometry, which is similar to the experimental one (Table 1). Similar values of the dihedral angles HH and HC and the corresponding spin–spin coupling constants 3J were found for 2, 4 and other examined compounds. The virtual spin–spin coupling constants of the carbons C(4) and C(8) with protons at C(9) are approximately equal to the half-sum of the constants 3J4Cd' and 3J4Cd.The long-range virtual spin–spin coupling constant 4Jobs = 1.2 Hz, of protons Hb, H'b at C(4) and C(8) with protons Hd, H'd at C(9) is observed for 1, 2, 4 and C (at {MeN})5 (cf. ref. 8). It was shown earlier5 that desymmetrisation of the system (for example, in going from C to D) resulted in the disappearance of virtual coupling, and the real coupling constants (4JHH = 2.2 Hz) for each link appeared; they are about two times as large and correspond to those for propane calculated using the dihedral angles C(9)–b and C(4)–d' close to 180° (Table 1).11 The bond lengths and bond angles in the crystal structures of 2 and 4 are very similar to those in the previously investigated derivatives A and B of dilactams of the bicyclo[3.3.0]octane series.2 The angles between five-membered rings in the structures of 2 and 4 are 72.3° and 71.8°, respectively, and are significantly smaller in comparison with the corresponding values in the A and B structures (110.3°).2 Both structures 2 and 4 are twisted; the pseudotorsion angles C(3)–C(4)–C(1)– C(2) and C(5)–C(4)–C(1)–C(6) are equal to 14.6°, 13.8° and 15.8°, 14.9°, respectively.‡ Crystallographic data for 2 and 4 at 25 °C: crystals of C13H18N2O6 2 are monoclinic, space group P21/c, a = 11.119(2) Å, b = 11.013(2) Å, c = 11.974(3) Å, b = 98.82(2)°, V = 1448.9(5) Å3, Z = 4, M= 298.29, dcalc = 1.367 g cm–3, m(MoKa) = 1.09 cm–1, F(000) = 632; crystals of C7H10N2O2 4 are orthorhombic, space group P212121, a = 6.603(4) Å, b = 9.841(4) Å, c = 10.704(3) Å, V = 695.5(5) Å3, Z = 4, M= 154.17, dcalc = 1.472 g cm–3, m(MoKa) = 1.10 cm–1, F(000) = 328.Intensities of 3525 reflections for 2 and 951 reflections for 4 were measured on a Siemens P3 diffractometer at 25 °C (l MoKa radiation, q/2q-scan technique, 2qmax 56°) and 3698 (for 2) or 951 (for 4) independent reflections were used in further calculations and refinement.The structures were solved by the direct method and refined by a full-matrix leastsquares against F2 in the anisotropic–isotropic approximation. Hydrogen atoms were located from the difference Fourier synthesis and refined in the isotropic approximation. The refinement converged to wR2 = 0.1081 and COF = 0.885 for all independent reflections [R1 = 0.0385 is calculated against F for the 2212 observed reflections with I > 2s(I)] for the structure of 2 and to wR2 = 0.0783 and COF = 1.077 for all independent reflections [R1 = 0.0294 is calculated against F for the 907 observed reflections with I > 2s(I)] for the structure of 4.All calculations were performed on an IBM PC/AT using the SHELXTL PLUS 5.0 program. Atomic coordinates, thermal parameters, bond lengths and bond angles have been deposited at the Cambridge Crystallographic Data Centre (CCDC).For details, see ‘Notice to Authors’, Mendeleev Commun., 1999, Issue 1. Any request to the CCDC for data should quote the full literature citation and the reference number 1135/44. It was found that molecules of 2 are capable of self-assembling as a heterochiral H-bonded infinite diagonal zigzag tape2 directed along the crystallographic c axis (Figure 4).The H-bond characteristics are N(1)–H(1N)···O(2''), (x, 1/2 – y, 1/2 + z); N(1)···O(2''), 2.886(3) Å; N(1)–H(1N)–O(2''), 167°; N(2)– H(2N)···O(1'), (x, 1/2 – y, –1/2 + z); N(2)···O(1'), 2.868(3) Å; N(2)–H(2N)–O(1'), 171°. Note that as a result of the packing effects ethyl groups in the CO2Et moiety are characterised by different conformations with the torsion angles C(10)–C(9)–O(4)–C(8) and C(13)– C(12)–O(6)–C(11) equal to 87.4° and 175.6°, respectively.Taking into account that the steric effect of the bulky CO2Et groups can play a significant role in the formation of the crystal structure (as it was observed early in A and B), we expected the desirable helical-type structure in parent dilactam 4.Indeed, as we found by X-ray diffraction analysis, dilactam 4 forms a crystalline conglomerate.‡ Similarly to the crystal structure of A and in contrast to that of 2, each molecule in the structure of 4 forms H-bonds with four neighbouring molecules. As a result, the molecules of dilactam 4 are assembled by two H-bonded orthogonal helices [N(1')–H(1N')···O(1), (1/2 + x, 3/2 – y, 1 – z); N(1')···O(1), 2.863(3) Å; N(1')–H(1N')–O(1), 172 Å; N(2)– aBy the general Karplus equation from the MM2 geometry; 3JHH, by the general Karplus equation,9 3JCH by the Karplus curve for norbornane.10 bFor 6.cFor 2. d 3JCH for carbon of MeN with a and b protons in compound C.5 eFor C.5 Table 1 Vicinal spin–spin coupling constants and dihedral angles in the investigated molecules.Protons and carbons 3J/Hz for 4 (and 2, 6, C) Dihedral angles (°) NMR Calculateda X-Ray for 4 (and 2) MM2 for 4 ac 5.02 (4.7)b 3.93 51.7 50.0 bc 1.45 (1.0)b 1.79 68.2 68.0 cd 2.57 (3.0)b 2.06 64.8 67.0 cd' 3.72 4.23 50.3 51.0 ae (0.0)c (0.0)d ~1.0 76.0 (71.3) 72.8 be (4.3)c (2.2)d ~4.0 42.2 (48.4) 42.7 C(9)a (0.0)c (0.0)e 1.2 70.1 (71.0) 69.0 C(9)b (7.0)c (7.0)e 9.3 171.1 (171.1) 172.7 C(4)d' [C(8)d] (5.2)c (4.4)e 9.2 172.6 (170.6) 171.0 C(4)d [C(8)d'] 4.1 52.5 (52.7) 51.9 Scheme 1 Reagents and conditions: i, 1,3,5-tris(4-methoxybenzyl)hexahydro- 1,3,5-triazine2 and CF3CO2H, 24 h at 100–120 °C; ii, Ce(NH4)2(NO3)6 (CAN) in MeCN–H2O, then NaHCO3; iii, KOH in MeOH, then HCl; iv, 20 min at 240–270 °C and 25 min at 290–300 °C in vacuo (20 Torr); v, KOH in EtOH, 12 h at 20 °C, separation of the precipitated K salt of 5 and its treatment with CF3CO2H in H2O; vi, 20 min at 240–270 °C and 25 min at 290–300 °C in vacuo (20 Torr) with sublimation of 6.HN NH X O O X A X = H B X = CO2Et MeN NMe X O O CO2Et C X = CO2Et D X = CO2 Na HN NH H H O O E [(EtO2C)2CH]2CH2 RN NR EtO2C O O CO2Et R = MeO CH2 i 1 ii v HN NH EtO2C O O CO2Et RN NR HO2C O O CO2H 2 5 HN NH HO2C O O CO2H RN NR H O O H 3 6 iii vi iv N N O O Hc Hc Ha Hb Ha Hb Hd Hd He He 4 ' ' ' ' ' 1 2 3 4 5 6 7 8 9 1' 2' 3' 4'Mendeleev Communications Electronic Version, Issue 3, 1999 (pp. 87–128) H(2N)···O(2'), (1/2 + x, 3/2 – y, 2 – z); N(2)···O(2'), 2.879(2) Å; N(2)–H(2N)–O(2'), 158°] into homochiral ‘corrugated’ layers parallel to the crystallographic ac plane (Figure 5).The crystal packing observed in 4 is very similar to the crystal structure of (–)-E.7 Thus, starting from an incorrect assumption (the possibility of formation of a helical type structure1), as well as Lehn and co-workers (who expected the formation of a six-membered ring architecture in E7), we, nevertheless, have achieved our main goal to obtain the desirable conglomerate crystals of 4.It should be noted that conglomerates were also found in the cases of 3,3,7,7-tetrabromobicyclo[3.3.1]nonane- 2,6-dione (space group P212121)8 and 4-hydroxy-5-ethyl-6- carbamoyl-7-amino-3-azabicyclo[3.2.1]oct-6-en-2-one dihydrate (space group P1).12 This work was supported by the Russian Foundation for Basic Research (grant no. 97-03-33021). References 1 R. G. Kostyanovsky, K. A. Lyssenko, G. K. Kadorkina, O. V. Lebedev, A. N. Kravchenko, I. I. Chervin and V. R. Kostyanovsky, Mendeleev Commun., 1998, 231. 2 R. G. Kostyanovsky, Yu. I. El’natanov, O. N. Krutius, K. A. Lyssenko and Yu. A. Strelenko, Mendeleev Commun., 1999, 70. 3 M. Tichy, L. Risdvan, P. Holy, J.Zavada, I. Cisarova and J. Podlaha, Tetrahedron Asymmetry, 1998, 9, 227. 4 G. Darnbrough, P. Knowles, S. P. O’Connor and F. J. Tierney, Tetrahedron, 1986, 42, 2339. 5 R. G. Kostyanovsky, Yu. I. El’natanov, I. I. Chervin and V. N. Voznesenskii, Izv. Akad. Nauk, Ser. Khim., 1996, 1037 (Russ. Chem. Bull., 1996, 45, 991). 6 R. G. Kostyanovsky, O. N. Krutius and Yu. I. El’natanov, Izv.Akad. Nauk, Ser. Khim., 1994, 2185 (Russ. Chem. Bull., 1994, 43, 2065). 7 M.-J. Brienne, J. Gabard, M. Leclercq, J.-M. Lehn, M. Cesario, C. Pascard, M. Cheve and G. Dutruc-Rosset, Tetrahedron Lett., 1994, 35, 8157. 8 H. Quast, C. Becker, E. Geissler, K. Knoll, E.-M. Peters, K. Peters and H. G. von Schnering, Liebigs Ann. Chem., 1994, 109. 9 C. A. G. Haasnoot, F. A. A. M. de Leeuw and C.Altona, Tetrahedron, 1980, 36, 2783. 10 R. Aydin and H. Günter, Magn. Reson. Chem., 1990, 28, 448. 11 M. Bartfield, A. M. Dean, C. J. Fallick, R. J. Spear, S. Sternhell and P. W. Westerman, J. Am. Chem. Soc., 1975, 97, 1482. 12 O. E. Nasakin, V. V. Pavlov, A. N. Lyschikov, P. M. Lukin, V. N. Khrustalev and M. Yu. Antipin, Khim. Geterotsikl. Soedin., 1996, 1326 [Chem. Heterocycl.Compd. (Engl. Transl.), 1996, 1136]. C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) O(1) O(2) O(3) O(4) O(5) O(6) N(1) N(2) H(1N) H(2N) H(5A) H(5B) H(2A) H(2B) H(9A) H(9B) H(10A) H(10B) H(10C) H(12A) H(12B) H(13A) H(13B) H(13C) H(7A) H(7B) Figure 2 Molecular structure of 2. Selected bond lengths (Å): O(1)–C(3) 1.234(2), O(2)–C(6) 1.236(2), N(1)–C(2) 1.457(2), N(1)–C(3) 1.336(2), N(2)–C(6) 1.335(2), N(2)–C(5) 1.459(2); selected bond angles (°): C(3)– N(1)–C(2) 127.2(1), C(6)–N(2)–C(5) 128.2(1), C(7)–C(1)–C(6) 112.0(1), C(7)–C(1)–C(2) 108.3(1), C(6)–C(1)–C(2) 109.0(1), N(1)–C(2)–C(1) 111.2(1), O(1)–C(3)–N(1) 122.4(1), O(1)–C(3)–C(4) 119.3(1), N(1)–C(3)– C(4) 118.2(1), C(7)–C(4)–C(5) 108.9(1), C(7)–C(4)–C(3) 112.2(1), C(5)– C(4)–C(3) 108.2(1), N(2)–C(5)–C(4) 110.6(1), O(2)–C(6)–N(2) 122.9(1), O(2)–C(6)–C(1) 119.2(1), N(2)–C(6)–C(1) 117.9(1), C(4)–C(7)–C(1) 107.3(1). C(1) C(2) C(3) C(4) C(5) C(6) C(7) H(7A) H(7B) H(1) H(4) H(5A) H(5B) H(2N) N(2) O(2) O(1) N(1) H(1N) H(2A) H(2B) Figure 3 Molecular structure of 4. Selected bond lengths (Å): O(1)–C(3) 1.231(2), O(2)–C(6) 1.236(2), N(1)–C(3) 1.335(2), N(1)–C(2) 1.454(2), N(2)–C(6) 1.338(2), N(2)–C(5) 1.460(2); selected bond angles (°): C(3)– N(1)–C(2) 126.3(1), C(6)–N(2)–C(5) 126.9(1), C(7)–C(1)–C(6) 112.4(1), C(7)–C(1)–C(2) 107.9(1), C(6)–C(1)–C(2) 109.5(1), N(1)–C(2)–C(1) 111.4(1), O(1)–C(3)–N(1) 122.1(2), O(1)–C(3)–C(4) 119.7(2), N(1)–C(3)– C(4) 118.2(1), C(3)–C(4)–C(7) 113.5(1), C(3)–C(4)–C(5) 108.6(1), C(7)– C(4)–C(5) 108.1(1), N(2)–C(5)–C(4) 110.5(1), O(2)–C(6)–N(2) 121.9(1), O(2)–C(6)–C(1) 120.2(1), N(2)–C(6)–C(1) 117.9(1), C(4)–C(7)–C(1) 106.8(1).H(2N) O(1') O(2) H(1N') N(1') N(2) N(1) H(1N) O(1) H(2N'') O(2'') N(2'') Figure 4 Diagonal zigzag tape in the crystal structure of 2. O(2') H(2N) H(2N'') N(2) O(2) N(1) H(1N) O(1) H(1N') N(1') Figure 5 Schematic diagram of the homochiral layer formation in the crystal structure of 4. For clarity, only molecules belonging to two orthogonal helices were selected. Received: 22th October 1998; Com. 98/1385 (8/08248K)

ISSN:0959-9436     

出版商:RSC    

年代:1999

数据来源: RSC