摘要:

J. CHEM. SOC. DALTON TRANS. 1987 2337 The Reaction of Di-2-pyridyl Ketone with Antimony(1ii) Fluoride. Preparation, Properties, Mossbauer Spectrum and Crystal Structure of Difluoro( methoxydi- 2-pyridylmethoxo-NN'O)antimony( 111) t Giuseppe Alonzo lstituto di Chimica Generale, Universita di Palermo, 1- 90 100 Palermo, Italy Nuccio Bertazzi lstituto di Chimica Generale, lnorganica e Analitica, Universita di Cagliari, 1-09 100 Cagliari, Italy Gabriella Bombieri * lstituto di Chimica Farmaceutica, Universita di Milano, 1-20 13 1 Milano, Italy Giuseppe Bruno Dipartimento di Chimica lnorganica e Struttura Molecolare, Universita di Messina, 1-98 100 Messina, Italy Di-2-pyridyl ketone (dpk) reacts with SbF, in methanol undergoing nucleophilic addition from the solvent. The resultant antimony(iii) complex SbF,[OC(OMe) (NC,H,),], involving the carbinol form of dpk as a fac-terdentate N,N,O ligand, has been characterized by Mossbauer spectroscopy and single-crystal X-ray analysis.It crystallizes in the orthorhombic system, space group Pnma, with a = 7.586( 1 ), b = 14.322( 1 ), c = 11.924( 1 ) A, and Z = 4. Least-squares refinement based on 71 0 observed reflections converged to R = 0.036 and R' = 0.033. The co-ordination polyhedron around Sb is a square pyramid [Sb-F 1.967(4), Sb-N 2.580(7), and Sb-O(1) 1.993(8) A]. The molecule lies on a crystallographic mirror plane. The interaction between di-2-pyridyl ketone (dpk) and metal ions (mainly transition-metal ions) has attracted considerable attention.'-'' Although dpk can potentially exhibit two modes of chelation, i.e.through the two pyridyl ring nitrogen atoms, or less likely through one ring nitrogen and the carbonyl oxygen, previous studies 2-6,8-12 indicated that only N,N co-ordination occurs in a variety of complexes containing the dpk unit as such. Moreover, depending upon the experimental conditions, the reaction with dpk has often been reported to afford formally 'hydrated' or 'alcoholated' metal-dpk c ~ m p l e x e s , ' - ~ * ~ ~ ~ ~ ~ ' * I 2 which do not show the characteristic ketonic group stretching in the i.r. spectrum. With these systems it was recognized2*, that dpk, (I), undergoes a metal-promoted nucleophilic addition. Q ,OH 6 ' O R (I) (I I) Besides retaining the possibility of acting as N,N-bidentate, the resulting carbinol form @I) should be considered also a potentially terdentate N,N,O ligand, and complexes of such terdentate systems have been proposed as possible inter- mediates in the metal-promoted reaction of the carbonyl group of dpk.None of the previous studies gave definite information about the structure of any metal-dpk complex. During our investigations on a series of antimony(rI1) halide complexes with multidentate ligands, we observed that dpk reacts with antimony trifluoride in methanol undergoing nucleophilic addition from the solvent and affording, almost quantitatively, the compound SbF,[OC(OMe)(NC,H,),]. t Supplementary data available: see Instructions for Authors, J. Chem. SOC., Dalton Trans., 1987, Issue 1, pp. xvii-xx. Here we report on the crystal and molecular structure of this complex which substantiates for the first time the ability of (11) to act as a monoanionic terdentate ligand.The com- pound has been further characterized by ','Sb Mossbauer and i.r. spectroscopy. Experimental Preparation of SbF,[OC(OMe)(NC,H,),].-Equimolar quantities of SbF, and dpk (2 mmol) were dissolved in methanol (20 cm3) at room temperature. After standing for a few days the solution afforded well formed crystals of the required compound (Found: C, 38.95; H, 3.05; N, 7.45. C,,H,,F2N20,Sb requires C, 38.45; H, 2.95; N, 7.4579, m.p. 121-123 "C, A = 7.0 S cm2 mol-' for a 1 mmol dmP3 solution in MeOH at 25 "C. Spectroscopic Measurements.-The i.r. spectra (4 000-180 cm-') were recorded as Nujol or hexachlorobutadiene mulls between CsI plates using a Perkin-Elmer 580 spectrophoto- meter.Relevant bands (cm-I): 1 595ms, 1 570mw [pyridyl ring, mixed v(C=N) and v(C==C)]; 1295w [in plane 6(C-H)?]; 763s [out-of-plane 6(C-H)]; 5 15ms, 480s [v(Sb-F)]; 325mw, 268mw, and 245mw [v(Sb-0) and v(Sb-N)]. The Mossbauer spectrum was obtained by cooling both the source (0.5 mCi Ca'2'mSn0,) and the absorber (12 mg Sb cm-') at liquid-nitrogen temperature and using the apparatus and methodology previously described.', X-Ray Structure Determination.-The crystal and refinement data are summarized in Table 1. The compound is in the form of transparent prisms stable to air. The X-ray intensity data were collected on a four-circle Siemens-Stoe automated diffracto- meter with graphite-monochromated Mo-K, radiation. The unit-cell parameters were determined on the basis of 25 strong reflections obtained by mounting the crystal at random, varying the orientation angles 0 and x in a 120" range with the detector position varying between 0 = 6 and 10".For the determin- ation of precise lattice parameters 20 strong reflections with 10 < 8 -= 15 were considered. The intensities of three standard reflections ( - 1 2 - 2; 3 2 6;2338 J. CHEM. SOC. DALTON TRANS. 1987 3 1 -7) monitored at 100-min intervals showed no greater fluctuation than that expected from Poisson statistics. The intensity data were corrected for Lorentz-polarization effects. The structure was solved using three-dimensional Patterson and Fourier techniques and refined by full-matrix least squares. Anisotropic thermal parameters were employed except for hydrogen atoms which were introduced at calculated positions (C-H 0.98 A) with fixed isotropic U = 0.06 A2.Anomalous dispersion for Sb was taken into account in the refinement, and atomic scattering factors were from ref. 14. Data processing and computations were carried out using the SHELX 76 program package.' Final positional parameters are presented in Table 2. Table 1. Crystal data Formula M Space group Crystal system alA blA CIA u/A3 z DJMg m-3 F W o ) Radiation @/A) Reflections measured Scan method Scan speed/" min-' Scan width/" Background counts per s of counting time 2~Ina,.l" R = ( W F O I - l ~ c l l / ~ ~ o ) R' = C W l F O I - I~c1)2/w~c121f Reflections observed [ I 3 30(1)] Weighting scheme, w p( Mo-KJcrn-' C12H1 ,FZNZOtSb 376.99 Pnma Orthorhombic 7.586( 1) 14.322( 1) 1 1.924( 1) 1295.5 4 1.93 728 0.710 69 1200 w e 1.20 1.20 10 50 710 2.5432[a2(FO) + O.OO0 104(F,)2]-' 0.036 0.03 3 19.8 Discussion The structure consists of discrete molecules as shown in Figure 1, each lying in a crystallographic mirror plane; in this way the asymmetric unit is half a molecule. The mirror plane bisects the molecule through Sb, 0(1), and C(1); the methoxy group [0(2) and C(2)] is somewhat out of the mirror plane with a statistical disposition of 50%.A perspective view of the molecule with the atom numbering scheme is shown in Figure 2 (only one of the two alternative positions of the methoxy group is represented; primed atoms are related to unprimed through the crystallographic mirror plane at x, 3 - y, 2).The bond distances and angles are reported in Table 3. The co-ordination polyhedron around Sb is a square pyramid, the base of which is formed by two fluorines and two nitrogens of the two pyridyl moieties (mirrored in pairs) and the apical position is occupied by the 'ketone' oxygen. The ligand (H,C,N),C(OMe)O-, originating from dpk, is thus acting as fac-terdentate with fairly narrow N-Sb-O( 1) [mirrored by N'-Sb-O( l)] and N-Sb-N' 'bite' angles of 68.2(2) and 75.5(3)", respectively. The Sb atom is 0.478( 1) A below the basal plane opposite the apical O( 1) atom, which is 1.449(8) A above. Table 2. Fractional atomic co-ordinates ( x lo4) with estimated standard deviations in parentheses X 1199(1) - 979(9) - 763(2) -2 409(1) -3 852(2) 21(7) 1 478(11) 1099(28) 2 284(24) 2 483(16) 270( 12) 76(16) * Population parameter 0.5.Y 2 500 2 500 2 500 2 178(6) 2 770( 1) 1541(3) 1397(5) 390( 12) 152(9) 668(7) 1639(6) 1136(10) z 3 093(1) 4 027(5) 5 196(1) 5 720(9) 5 a ( 2 ) 2 180(4) 4 795(6) 6 710(12) 5 943(13) 5 003(10) 5 535(7) 6 520(9) WJ. CHEM. SOC. DALTON TRANS. 1987 2339 I Table 3. Bond distances (A) and angles (") F-Sb-F' N-Sb-N' F-Sb-N F-Sb-N' F-SbO( 1) N-SbO( 1) Sb-N-C(9) Sb-N-C(10) sb-O( 1)-C( 1) N-C(9)-C(8) C(9W(8W(7) 1.967(4) 2.580(7) 1.993(8) 1.32(1) 1.32( 1) 1.35(2) 1.33(2) 88.5(3) 7533) 92.6(2) 154.2(2) 86.1(2) 68.2(2) 133.0(8) 108.0(5) 117.3(7) 122( 1) 120( 1) 119(1) 120( 1) 118.9(9) 126(1) 113.2(8) 109.0(7) 94.1(6) 108.8(9) 108.9(9) 130(1) 120(1) Figure 2. Perspective view of a molecule of the complex with the atom numbering scheme The lone electron pair is assumed to lie trans to the Sb-0(1) bond.The displacement is larger than that observed in the com- pound SbF3[ONC5H,(0Me-4)],.H,O '' which has a similar pyramidal geometry in which the antimony atom lies 0.29 A above the bond plane formed by a 0 2 F 2 grouping of donor atoms. The Sb-F distance [1.968(7) A] is equal to that reported for Sb-F(basa1) in SbF3[ONC,H,(OMe-4)],.H,0 l 6 [1.968(5) A] and in SbF(O,C,H,)(phen) [ 1.965(7) A], and intermediate between the values ranglng from 1.938(2) to 1.997(2) 8, observed in SbF,(phen)(tu) I 8 (C6H,022 - = pyrocatecholate dianion, phen = 1,lO-phenanthroline, and tu = thiourea). The Sb-N bond distance [2.584(7) A] can be compared with those observed for the phen ligand which is chelating asym- metrically to the antimony(II1) atom in SbF(O,C,H,)(phen) [2.448(9) and 2.569(9) in the cationic species containing two phen units [Sb(O,C,H,)(phen),]' [2.423(7), 2.592(5), and 2.467(7), 2.694(5) A, respectivelyJ,'Y in SbF,(phen)(tu) [2.556(6) and 2.731(3) A] I s as well with the less geometrically constrained Sb-N distances of 2.53 and 2.64 A found in SbCl, complexes of aniline.20 It is of interest that the value of the Sb-O(1) bond distance [1.990(8) A] trans to the assumed site of the lone pair is com- parable to the value [2.007(8) A] found for Sb-0 trans to the lone pair in SbF(02C,H,)(phen).'7 Taking also into account that in SbF3[ONC5H,(OMe-4)]2-H20 l6 the Sb-F(apica1) distance is particularly short, 1.905(5) A, it seems that the J L I I 1 I - 20 -10 0 +10 + 20 Velocity/mm s-1 Figure 3.The Mossbauer spectrum of SbF,[OC(OMe)(NC,H,),] observation of a shortening of Sb-X bond distances trans to the lone-pair position 2 1 is valid for these pyramidal SbX5E antimony(II1) species. This assumption was not verified for SbF,(phen)(tu) where the interaction with an additional donor atom (a sulphur of the thiourea molecule at large distance) modifies the lone-pair position which is no longer really trans to a particular Sb-X bond. The geometry of the ligand appears normal. The two planar pyridyl moieties are inclined to each other at 75.1(3)' (dihedral angle) and 118.4(3)O with respect to the co-ordination square plane. The bond lengths around the sp3-hybridized carbon atom C(l) are normal for single C-C [C(l)-C(l0) 1.51(1) A] and C-0 [C(l)-0(1) 1.40(1) and C(1)-0(2) 1.46(2) A], while the angles C( 10)-C( 1)-0(2) and C( 10')-C( 1)-0(2) deviate noticeably from regular tetrahedral values, being 93.2(5)' and 124.4(5)", respectively. The Sb-O(l)-C( 1) angle [ 117.3(3)'] is indicative of a possible sp2 hybridization of the oxygen atom.Previous observations on Sb-0 and Sb-N bond distances indicate that antimony(1rr) fits fairly well into the terdentate N,N,O system. However, the present ligand appears somewhat 'strained' as judged from the asymmetry of the angles (those external to the pyridyl ring) at C(10) and N: C(l)-C(lO)-C(6) 126(1), C(l)-C(lO)-N 113.2(8), Sb-N-C(10) 108.0(5), and Sb-N-C(9) 133.0(9)". However, despite the above distortions, Sb lies sensibly in the plane of the pyridyl ring.Spectroscopic Data.-The alcoholysis of dpk is reflected in the disappearance of the ketonic v(C-0) band from the i.r. spectrum of the present compound (see Experimental section). The spectrum also shows an increase in the pyridyi-ring mixed C=N and C=C stretching frequencies (1 578s and 1 565m cm-' for free dpk), as well as in the 6(C-H) out-of-plane modes (753s and 742s cm-' for free dpk) previously observed for metal complexes of both dpk and its 'reacted' forms. '-I2 A distinctive feature of previously reported data 6*1 is the considerable reduction in intensity of the 6(C-H) in-plane modes (1 325s cm-I for free dpk). In the skeletal region, whereas the asym- metric and symmetric SbF stretchings can easily be assigned, a clear distinction between v(Sb-N) and v(Sb-0) modes cannot be made.The Mossbauer spectrum of the compound is shown in Figure 3 together with the calculated one corresponding to the best fitted parameters: isomer shift (is.) (relative to the source) = - 15.2 mm s-l, eQVzz = 19.5 mm s-', and q -c 0.2. These values may be compared with those measured for SbF-2340 J. CHEM. SOC. DALTON TRANS. 1987 (02C6H4)(phen) and [Sb(02C6H4)(phen),] + (is. = - 14.3 and - 14.0; eQVZZ = 15.4 and 16.1 mm s-l, respectively 19) where Sb”’ is co-ordinated by second-row donor atoms and crystallographic data 17,19 also show the presence of a stereo- chemically active lone pair. Also of interest are the parameters reported 22 for SbF, (is. = - 14.8, eQV,, = 19.1 mm s-I).The structure of the latter 23 consists of SbF, pyramidal units, with short Sb-F bonds nearly at right angles, and three additional Sb F contacts providing an overall C3” symmetry. The lone pair can be assumed to lie opposite to the three short SbF bonds along the C,, axis. We think that the SbF, and SbF,O units found in antimony trifluoride and in the present compound respectively are essentially similar but in the latter the reduced symmetry results in a lone pair probably located roughly opposite to the oxygen atom. Although this could result in a non-zero value of the electric-field-gradient asymmetry parameter, q, the small con- tribution from the Sb-F or Sb-0 bonds with respect to that from the lone-pair electron density in our opinion justifies the very small q value estimated from the fitting procedure.Acknowledgements Support from the Italian Minister0 della Pubblica Istruzione is acknowledged. References 1 R. R. Osborne and W. R. McWhinnie, J. Chem. Soc. A, 1967,2075. 2 M. C. Feller and R. Robson, Aust. J. Chem., 1968, 21, 2919. 3 M. C. Feller and R. Robson, Aust. J. Chem., 1970, 23, 1997. 4 I. J. Bakker, M. C. Feller, and R. Robson, J. Inorg. Nucl. Chem., 1971, 33, 747. 5 J. D. Ortego and D. L. Perry, J. Inorg. Nucl. Chem., 1973, 35, 3031. 6 J. D. Ortego, D. D. Wasters, and C. H. Steele, J. Inorg. Nucl. Chem., 7 D. L. Perry and R. A. Geanangel, J. Znorg. Nucl. Chem., 1974,36,205. 8 V. Rattanaphani and W. R. McWhinnie, Inorg. Chim. Acta, 1974,9, 9 G. C. Pappalardo and A. Seminara, J. Inorg. Nucl. Chem., 1976,38, 10 J.D. Ortego, S. Upalawanna, and S. Amanollahi, J. Inorg. Nucl. 11 J. D. Ortego and M. Seymour, Polyhedron, 1982, 1, 21. 12 D. L. Perry, J. L. Margrave, and D. W. Bonnell, Znorg. Chim. Acta, 13 G. Alonzo, N. Bertazzi, and F. Huber, Can. J. Spectrosc., 1985,30,21. 14 ‘International Tables for X-Ray Crystallography,’ 2nd edn., Kynoch 15 G. M. Sheldrick SHELX 76, University of Cambridge, 1976. 16 J. C. Dewan, A. J. Edwards, J. E. Guerchais, and F. Petillon, J. Chem. 17 H. Preut, F. Huber, G. Alonzo, and N. Bertazzi, Acta Crystallogr., 18 G. Bombieri, G. Bruno, F. Nicolo, G. Alonzo, and N. Bertazzi, 19 F. Huber, H. Preut, G. Alonzo, and N. Bertazzi, Znorg. Chim. Acta, 20 R. Hulme, D. Mullen, and J. C. Scruton, Acta Crystallogr., Sect. A, 21 R. J. Gillespie, J.Chem. Soc., 1963, 4672. 22 J. G. Ballard, T. Birchall, R. Fourcade, and G. Mascherpa, J. Chem. 23 A. J. Edwards, J. Chem. Soc. A, 1970, 2751. 1974, 36, 751. 239. 1993. Chem., 1979,41, 593. 1985, 101, L1. Press, Birmingham, 1974, vol. 4, p. 101. Soc., Dalton Trans., 1975, 2293. Sect. B, 1982, 38, 935. J. Chem. Soc., Dalton Trans., submitted for publication. 1985, 102, 181. 1969, 25, S171. Soc., Dalton Trans., 1976, 2409. Received 6th October 1986; Paper 611961 J. CHEM. SOC. DALTON TRANS. 1987 2337 The Reaction of Di-2-pyridyl Ketone with Antimony(1ii) Fluoride. Preparation, Properties, Mossbauer Spectrum and Crystal Structure of Difluoro( methoxydi- 2-pyridylmethoxo-NN'O)antimony( 111) t Giuseppe Alonzo lstituto di Chimica Generale, Universita di Palermo, 1- 90 100 Palermo, Italy Nuccio Bertazzi lstituto di Chimica Generale, lnorganica e Analitica, Universita di Cagliari, 1-09 100 Cagliari, Italy Gabriella Bombieri * lstituto di Chimica Farmaceutica, Universita di Milano, 1-20 13 1 Milano, Italy Giuseppe Bruno Dipartimento di Chimica lnorganica e Struttura Molecolare, Universita di Messina, 1-98 100 Messina, Italy Di-2-pyridyl ketone (dpk) reacts with SbF, in methanol undergoing nucleophilic addition from the solvent.The resultant antimony(iii) complex SbF,[OC(OMe) (NC,H,),], involving the carbinol form of dpk as a fac-terdentate N,N,O ligand, has been characterized by Mossbauer spectroscopy and single-crystal X-ray analysis. It crystallizes in the orthorhombic system, space group Pnma, with a = 7.586( 1 ), b = 14.322( 1 ), c = 11.924( 1 ) A, and Z = 4.Least-squares refinement based on 71 0 observed reflections converged to R = 0.036 and R' = 0.033. The co-ordination polyhedron around Sb is a square pyramid [Sb-F 1.967(4), Sb-N 2.580(7), and Sb-O(1) 1.993(8) A]. The molecule lies on a crystallographic mirror plane. The interaction between di-2-pyridyl ketone (dpk) and metal ions (mainly transition-metal ions) has attracted considerable attention.'-'' Although dpk can potentially exhibit two modes of chelation, i.e. through the two pyridyl ring nitrogen atoms, or less likely through one ring nitrogen and the carbonyl oxygen, previous studies 2-6,8-12 indicated that only N,N co-ordination occurs in a variety of complexes containing the dpk unit as such. Moreover, depending upon the experimental conditions, the reaction with dpk has often been reported to afford formally 'hydrated' or 'alcoholated' metal-dpk c ~ m p l e x e s , ' - ~ * ~ ~ ~ ~ ~ ' * I 2 which do not show the characteristic ketonic group stretching in the i.r.spectrum. With these systems it was recognized2*, that dpk, (I), undergoes a metal-promoted nucleophilic addition. Q ,OH 6 ' O R (I) (I I) Besides retaining the possibility of acting as N,N-bidentate, the resulting carbinol form @I) should be considered also a potentially terdentate N,N,O ligand, and complexes of such terdentate systems have been proposed as possible inter- mediates in the metal-promoted reaction of the carbonyl group of dpk. None of the previous studies gave definite information about the structure of any metal-dpk complex.During our investigations on a series of antimony(rI1) halide complexes with multidentate ligands, we observed that dpk reacts with antimony trifluoride in methanol undergoing nucleophilic addition from the solvent and affording, almost quantitatively, the compound SbF,[OC(OMe)(NC,H,),]. t Supplementary data available: see Instructions for Authors, J. Chem. SOC., Dalton Trans., 1987, Issue 1, pp. xvii-xx. Here we report on the crystal and molecular structure of this complex which substantiates for the first time the ability of (11) to act as a monoanionic terdentate ligand. The com- pound has been further characterized by ','Sb Mossbauer and i.r. spectroscopy. Experimental Preparation of SbF,[OC(OMe)(NC,H,),].-Equimolar quantities of SbF, and dpk (2 mmol) were dissolved in methanol (20 cm3) at room temperature. After standing for a few days the solution afforded well formed crystals of the required compound (Found: C, 38.95; H, 3.05; N, 7.45.C,,H,,F2N20,Sb requires C, 38.45; H, 2.95; N, 7.4579, m.p. 121-123 "C, A = 7.0 S cm2 mol-' for a 1 mmol dmP3 solution in MeOH at 25 "C. Spectroscopic Measurements.-The i.r. spectra (4 000-180 cm-') were recorded as Nujol or hexachlorobutadiene mulls between CsI plates using a Perkin-Elmer 580 spectrophoto- meter. Relevant bands (cm-I): 1 595ms, 1 570mw [pyridyl ring, mixed v(C=N) and v(C==C)]; 1295w [in plane 6(C-H)?]; 763s [out-of-plane 6(C-H)]; 5 15ms, 480s [v(Sb-F)]; 325mw, 268mw, and 245mw [v(Sb-0) and v(Sb-N)]. The Mossbauer spectrum was obtained by cooling both the source (0.5 mCi Ca'2'mSn0,) and the absorber (12 mg Sb cm-') at liquid-nitrogen temperature and using the apparatus and methodology previously described.', X-Ray Structure Determination.-The crystal and refinement data are summarized in Table 1.The compound is in the form of transparent prisms stable to air. The X-ray intensity data were collected on a four-circle Siemens-Stoe automated diffracto- meter with graphite-monochromated Mo-K, radiation. The unit-cell parameters were determined on the basis of 25 strong reflections obtained by mounting the crystal at random, varying the orientation angles 0 and x in a 120" range with the detector position varying between 0 = 6 and 10". For the determin- ation of precise lattice parameters 20 strong reflections with 10 < 8 -= 15 were considered.The intensities of three standard reflections ( - 1 2 - 2; 3 2 6;2338 J. CHEM. SOC. DALTON TRANS. 1987 3 1 -7) monitored at 100-min intervals showed no greater fluctuation than that expected from Poisson statistics. The intensity data were corrected for Lorentz-polarization effects. The structure was solved using three-dimensional Patterson and Fourier techniques and refined by full-matrix least squares. Anisotropic thermal parameters were employed except for hydrogen atoms which were introduced at calculated positions (C-H 0.98 A) with fixed isotropic U = 0.06 A2. Anomalous dispersion for Sb was taken into account in the refinement, and atomic scattering factors were from ref. 14. Data processing and computations were carried out using the SHELX 76 program package.' Final positional parameters are presented in Table 2.Table 1. Crystal data Formula M Space group Crystal system alA blA CIA u/A3 z DJMg m-3 F W o ) Radiation @/A) Reflections measured Scan method Scan speed/" min-' Scan width/" Background counts per s of counting time 2~Ina,.l" R = ( W F O I - l ~ c l l / ~ ~ o ) R' = C W l F O I - I~c1)2/w~c121f Reflections observed [ I 3 30(1)] Weighting scheme, w p( Mo-KJcrn-' C12H1 ,FZNZOtSb 376.99 Pnma Orthorhombic 7.586( 1) 14.322( 1) 1 1.924( 1) 1295.5 4 1.93 728 0.710 69 1200 w e 1.20 1.20 10 50 710 2.5432[a2(FO) + O.OO0 104(F,)2]-' 0.036 0.03 3 19.8 Discussion The structure consists of discrete molecules as shown in Figure 1, each lying in a crystallographic mirror plane; in this way the asymmetric unit is half a molecule.The mirror plane bisects the molecule through Sb, 0(1), and C(1); the methoxy group [0(2) and C(2)] is somewhat out of the mirror plane with a statistical disposition of 50%. A perspective view of the molecule with the atom numbering scheme is shown in Figure 2 (only one of the two alternative positions of the methoxy group is represented; primed atoms are related to unprimed through the crystallographic mirror plane at x, 3 - y, 2). The bond distances and angles are reported in Table 3. The co-ordination polyhedron around Sb is a square pyramid, the base of which is formed by two fluorines and two nitrogens of the two pyridyl moieties (mirrored in pairs) and the apical position is occupied by the 'ketone' oxygen.The ligand (H,C,N),C(OMe)O-, originating from dpk, is thus acting as fac-terdentate with fairly narrow N-Sb-O( 1) [mirrored by N'-Sb-O( l)] and N-Sb-N' 'bite' angles of 68.2(2) and 75.5(3)", respectively. The Sb atom is 0.478( 1) A below the basal plane opposite the apical O( 1) atom, which is 1.449(8) A above. Table 2. Fractional atomic co-ordinates ( x lo4) with estimated standard deviations in parentheses X 1199(1) - 979(9) - 763(2) -2 409(1) -3 852(2) 21(7) 1 478(11) 1099(28) 2 284(24) 2 483(16) 270( 12) 76(16) * Population parameter 0.5. Y 2 500 2 500 2 500 2 178(6) 2 770( 1) 1541(3) 1397(5) 390( 12) 152(9) 668(7) 1639(6) 1136(10) z 3 093(1) 4 027(5) 5 196(1) 5 720(9) 5 a ( 2 ) 2 180(4) 4 795(6) 6 710(12) 5 943(13) 5 003(10) 5 535(7) 6 520(9) WJ.CHEM. SOC. DALTON TRANS. 1987 2339 I Table 3. Bond distances (A) and angles (") F-Sb-F' N-Sb-N' F-Sb-N F-Sb-N' F-SbO( 1) N-SbO( 1) Sb-N-C(9) Sb-N-C(10) sb-O( 1)-C( 1) N-C(9)-C(8) C(9W(8W(7) 1.967(4) 2.580(7) 1.993(8) 1.32(1) 1.32( 1) 1.35(2) 1.33(2) 88.5(3) 7533) 92.6(2) 154.2(2) 86.1(2) 68.2(2) 133.0(8) 108.0(5) 117.3(7) 122( 1) 120( 1) 119(1) 120( 1) 118.9(9) 126(1) 113.2(8) 109.0(7) 94.1(6) 108.8(9) 108.9(9) 130(1) 120(1) Figure 2. Perspective view of a molecule of the complex with the atom numbering scheme The lone electron pair is assumed to lie trans to the Sb-0(1) bond. The displacement is larger than that observed in the com- pound SbF3[ONC5H,(0Me-4)],.H,O '' which has a similar pyramidal geometry in which the antimony atom lies 0.29 A above the bond plane formed by a 0 2 F 2 grouping of donor atoms.The Sb-F distance [1.968(7) A] is equal to that reported for Sb-F(basa1) in SbF3[ONC,H,(OMe-4)],.H,0 l 6 [1.968(5) A] and in SbF(O,C,H,)(phen) [ 1.965(7) A], and intermediate between the values ranglng from 1.938(2) to 1.997(2) 8, observed in SbF,(phen)(tu) I 8 (C6H,022 - = pyrocatecholate dianion, phen = 1,lO-phenanthroline, and tu = thiourea). The Sb-N bond distance [2.584(7) A] can be compared with those observed for the phen ligand which is chelating asym- metrically to the antimony(II1) atom in SbF(O,C,H,)(phen) [2.448(9) and 2.569(9) in the cationic species containing two phen units [Sb(O,C,H,)(phen),]' [2.423(7), 2.592(5), and 2.467(7), 2.694(5) A, respectivelyJ,'Y in SbF,(phen)(tu) [2.556(6) and 2.731(3) A] I s as well with the less geometrically constrained Sb-N distances of 2.53 and 2.64 A found in SbCl, complexes of aniline.20 It is of interest that the value of the Sb-O(1) bond distance [1.990(8) A] trans to the assumed site of the lone pair is com- parable to the value [2.007(8) A] found for Sb-0 trans to the lone pair in SbF(02C,H,)(phen).'7 Taking also into account that in SbF3[ONC5H,(OMe-4)]2-H20 l6 the Sb-F(apica1) distance is particularly short, 1.905(5) A, it seems that the J L I I 1 I - 20 -10 0 +10 + 20 Velocity/mm s-1 Figure 3.The Mossbauer spectrum of SbF,[OC(OMe)(NC,H,),] observation of a shortening of Sb-X bond distances trans to the lone-pair position 2 1 is valid for these pyramidal SbX5E antimony(II1) species. This assumption was not verified for SbF,(phen)(tu) where the interaction with an additional donor atom (a sulphur of the thiourea molecule at large distance) modifies the lone-pair position which is no longer really trans to a particular Sb-X bond. The geometry of the ligand appears normal.The two planar pyridyl moieties are inclined to each other at 75.1(3)' (dihedral angle) and 118.4(3)O with respect to the co-ordination square plane. The bond lengths around the sp3-hybridized carbon atom C(l) are normal for single C-C [C(l)-C(l0) 1.51(1) A] and C-0 [C(l)-0(1) 1.40(1) and C(1)-0(2) 1.46(2) A], while the angles C( 10)-C( 1)-0(2) and C( 10')-C( 1)-0(2) deviate noticeably from regular tetrahedral values, being 93.2(5)' and 124.4(5)", respectively. The Sb-O(l)-C( 1) angle [ 117.3(3)'] is indicative of a possible sp2 hybridization of the oxygen atom.Previous observations on Sb-0 and Sb-N bond distances indicate that antimony(1rr) fits fairly well into the terdentate N,N,O system. However, the present ligand appears somewhat 'strained' as judged from the asymmetry of the angles (those external to the pyridyl ring) at C(10) and N: C(l)-C(lO)-C(6) 126(1), C(l)-C(lO)-N 113.2(8), Sb-N-C(10) 108.0(5), and Sb-N-C(9) 133.0(9)". However, despite the above distortions, Sb lies sensibly in the plane of the pyridyl ring. Spectroscopic Data.-The alcoholysis of dpk is reflected in the disappearance of the ketonic v(C-0) band from the i.r. spectrum of the present compound (see Experimental section). The spectrum also shows an increase in the pyridyi-ring mixed C=N and C=C stretching frequencies (1 578s and 1 565m cm-' for free dpk), as well as in the 6(C-H) out-of-plane modes (753s and 742s cm-' for free dpk) previously observed for metal complexes of both dpk and its 'reacted' forms.'-I2 A distinctive feature of previously reported data 6*1 is the considerable reduction in intensity of the 6(C-H) in-plane modes (1 325s cm-I for free dpk). In the skeletal region, whereas the asym- metric and symmetric SbF stretchings can easily be assigned, a clear distinction between v(Sb-N) and v(Sb-0) modes cannot be made. The Mossbauer spectrum of the compound is shown in Figure 3 together with the calculated one corresponding to the best fitted parameters: isomer shift (is.) (relative to the source) = - 15.2 mm s-l, eQVzz = 19.5 mm s-', and q -c 0.2.These values may be compared with those measured for SbF-2340 J. CHEM. SOC. DALTON TRANS. 1987 (02C6H4)(phen) and [Sb(02C6H4)(phen),] + (is. = - 14.3 and - 14.0; eQVZZ = 15.4 and 16.1 mm s-l, respectively 19) where Sb”’ is co-ordinated by second-row donor atoms and crystallographic data 17,19 also show the presence of a stereo- chemically active lone pair. Also of interest are the parameters reported 22 for SbF, (is. = - 14.8, eQV,, = 19.1 mm s-I). The structure of the latter 23 consists of SbF, pyramidal units, with short Sb-F bonds nearly at right angles, and three additional Sb F contacts providing an overall C3” symmetry. The lone pair can be assumed to lie opposite to the three short SbF bonds along the C,, axis. We think that the SbF, and SbF,O units found in antimony trifluoride and in the present compound respectively are essentially similar but in the latter the reduced symmetry results in a lone pair probably located roughly opposite to the oxygen atom.Although this could result in a non-zero value of the electric-field-gradient asymmetry parameter, q, the small con- tribution from the Sb-F or Sb-0 bonds with respect to that from the lone-pair electron density in our opinion justifies the very small q value estimated from the fitting procedure. Acknowledgements Support from the Italian Minister0 della Pubblica Istruzione is acknowledged. References 1 R. R. Osborne and W. R. McWhinnie, J. Chem. Soc. A, 1967,2075. 2 M. C. Feller and R. Robson, Aust. J. Chem., 1968, 21, 2919. 3 M. C. Feller and R. Robson, Aust. J. Chem., 1970, 23, 1997. 4 I. J. Bakker, M. C. Feller, and R. Robson, J. Inorg. Nucl. Chem., 1971, 33, 747. 5 J. D. Ortego and D. L. Perry, J. Inorg. Nucl. Chem., 1973, 35, 3031. 6 J. D. Ortego, D. D. Wasters, and C. H. Steele, J. Inorg. Nucl. Chem., 7 D. L. Perry and R. A. Geanangel, J. Znorg. Nucl. Chem., 1974,36,205. 8 V. Rattanaphani and W. R. McWhinnie, Inorg. Chim. Acta, 1974,9, 9 G. C. Pappalardo and A. Seminara, J. Inorg. Nucl. Chem., 1976,38, 10 J. D. Ortego, S. Upalawanna, and S. Amanollahi, J. Inorg. Nucl. 11 J. D. Ortego and M. Seymour, Polyhedron, 1982, 1, 21. 12 D. L. Perry, J. L. Margrave, and D. W. Bonnell, Znorg. Chim. Acta, 13 G. Alonzo, N. Bertazzi, and F. Huber, Can. J. Spectrosc., 1985,30,21. 14 ‘International Tables for X-Ray Crystallography,’ 2nd edn., Kynoch 15 G. M. Sheldrick SHELX 76, University of Cambridge, 1976. 16 J. C. Dewan, A. J. Edwards, J. E. Guerchais, and F. Petillon, J. Chem. 17 H. Preut, F. Huber, G. Alonzo, and N. Bertazzi, Acta Crystallogr., 18 G. Bombieri, G. Bruno, F. Nicolo, G. Alonzo, and N. Bertazzi, 19 F. Huber, H. Preut, G. Alonzo, and N. Bertazzi, Znorg. Chim. Acta, 20 R. Hulme, D. Mullen, and J. C. Scruton, Acta Crystallogr., Sect. A, 21 R. J. Gillespie, J. Chem. Soc., 1963, 4672. 22 J. G. Ballard, T. Birchall, R. Fourcade, and G. Mascherpa, J. Chem. 23 A. J. Edwards, J. Chem. Soc. A, 1970, 2751. 1974, 36, 751. 239. 1993. Chem., 1979,41, 593. 1985, 101, L1. Press, Birmingham, 1974, vol. 4, p. 101. Soc., Dalton Trans., 1975, 2293. Sect. B, 1982, 38, 935. J. Chem. Soc., Dalton Trans., submitted for publication. 1985, 102, 181. 1969, 25, S171. Soc., Dalton Trans., 1976, 2409. Received 6th October 1986; Paper 611961

ISSN:1477-9226    

DOI:10.1039/DT9870002337

出版商:RSC    

年代:1987

数据来源: RSC