DALTON FULL PAPER J. Chem. Soc., Dalton Trans., 1999, 183–190 183 5,59-Dicyano-2,29-bipyridine silver complexes: discrete units or co-ordination polymers through a chelating and/or bridging metal–ligand interaction He-Ping Wu,a Christoph Janiak,*a Gerd Rheinwald b and Heinrich Lang b a Institut für Anorganische und Analytische Chemie, Universität Freiburg, Albertstr. 21, D-79104 Freiburg, Germany. E-mail: janiak@uni-freiburg.de b Institut für Chemie, Zehrstuhl für Anorganische Chemie, Technische Universität Chemnitz, Strasse der Nationen 62, D-09111 Chemnitz, Germany Received 24th September 1998, Accepted 6th November 1998 The ambidentate ligand 5,59-dicyano-2,29-bipyridine (L) was found to function as a bi-, tri- or tetra-dentate chelate or chelate/bridging ligand in the co-ordination of silver ions.The mode of co-ordination depends on the anion and the crystallization conditions and was elucidated by single crystal X-ray diVractometry. With metal-co-ordinating anions such as NO3 2 and CF3SO3 2 a tridentate co-ordination mode of L is observed which involves the two bipyridine nitrogen donor atoms and one cyano group.The latter bridges to a neighboring silver center so that a one-dimensional co-ordination polymer results. For NO3 2 this co-ordination polymer forms a 21 helix. With less co-ordinating anions such as BF4 2 and PF6 2 monomeric bis-chelate complexes are obtained, where L assumes a bidentate co-ordination mode involving only the bipyridine nitrogen donor atoms.In the case of the PF6 2 anion a variation in the solvent of crystallization also produced a two-dimensional hexagonal co-ordination polymer where L functions as a tetradentate ligand using all four nitrogen donor atoms in chelation and bridging to the silver centers. Introduction Metal complexes of chelating 2,29-bipyridine or bridging 4,49-bipyridine or derivatives thereof are of constant and general interest in metal co-ordination chemistry.1 4,49-Bipyridine has recently gained considerable interest in the synthesis of (rectangular) two-dimensional network structures.2 The generation of such frameworks is a promising path in the search for stable microporous metal–organic networks that exhibit reversible guest exchange and possibly selective catalytic activity.3,4 Ligands containing CN-donors such as 4,49-dicyanobiphenyl, 1,3,5-tris(4-cyanophenylethynyl)benzene (TEB) and others are also excellent bridging ligands to synthesize porous N N N N CN NC NC CN CN N N CN NC co-ordination polymers.5 A highlighted example is the coordination of TEB with AgSO3CF3 in benzene that led to the isolation of the compound [Ag(CF3SO3)(TEB)]?2C6H6,6 which exhibits 15 Å channels and is porous to benzene exchange.We investigate here the co-ordination chemistry of 5,59- dicyano-2,29-bipyridine (L). This ambidentate ligand can be thought of as combining the ligating properties of the chelating 2,29-bipyridine and the bridging 4,49-dicyanobiphenyl ligand.The idea behind the use of such ambidentate ligands is to have cross-connecting blocks (tectons) for co-ordination polymers based on the endo chelation of two ligands with an appropriate metal center (1) or to supply functional donor atoms within the walls of the co-ordination polymer when the ligands are solely exo bridging (2). Our research has been concerned with the utilization of ambidentate endo-chelating/exo-bridging modified 2,29-bipyridine ligands such as 5,59-diamino-2,29-bipyridine 7 or 2,29-dimethyl- 4,49-bipyrimidine 8 and ligands of the tris(pyrazolyl)borate type for the assembly of metal co-ordination polymers.9,10 In this paper we describe the results of synthetic and structural studies of metal complexes with the ligand 5,59-dicyano-2,29- bipyridine (L) and try to elucidate the factors which lead to bridging, chelating or simultaneous bridging/chelating metal co-ordination.As a metal we have chosen silver(I) which together with copper(I) is a preferred ligand linker because of their favored tetrahedral co-ordination mode.5,11–13 In addition, silver can also assume a linear co-ordination 13 and would thus be ideal for testing the formation of cross-linkers as depicted in 1. Results and discussion The synthesis of 5,59-dicyano-2,29-bipyridine as reported in the literature is the reaction of 2,29-bipyridine-5,59-dicarboxamide with POCl3 in CHCl3 under sonication (50 kHz) to give the product in 86% yield.14 Another method is the sublimation of a mixture of 2,29-bipyridine-5,59-dicarboxamide and P4O10184 J.Chem. Soc., Dalton Trans., 1999, 183–190 under vacuum at a temperature of 300 8C.15 However, a twofold dehydration treatment and a two-fold sublimation of the crude (sublimed) product was found necessary to obtain the product in satisfactory purity. This finally gave the dicyanobipyridine in a low yield of only 29%.Furthermore, if more than 0.5 g of the dicarboxamide was used in the dehydration reaction with P4O10 this resulted in a further decrease of the yield of the product. Thus, we report here a modified method which is based on a two-times dehydration treatment of the dicarboxamide, first with a trifluoroacetic anhydride–pyridine system and then with P4O10 [eqn. (1)]. The initial dehydrated crude product N N M N N NC CN C C N N N N M M N N N N N N M M NC NC CN CN NC NC CN CN 1 2 is obtained in high yield.This crude product was then again dehydrated with P4O10 at 0.2 mbar/200 8C to give the final product in 43% yield. This method has the advantage of a higher yield (compared to the literature),15 the possibility of starting with an increased amount of the dicarboxamide, and the use of a lower sublimation temperature. The reaction routes of 5,59-dicyano-2,29-bipyridine (L) with silver metal salts are summarized in Scheme 1. The reaction of silver nitrate or silver trifluoromethane sulfonate with L in a 2 : 1 metal-to-ligand stoichiometry in ethanol or toluene, respectively, led to the formation of compounds which feature a 1 : 1 metal-to-ligand ratio (3 and 4).Both reactions were carried out by heating the mixture of reactants to 95 8C for 24 h and then slowly cooling to room temperature (RT) at a rate of 1 8C h21. Treating L with an excess of silver salts of less co-ordinating tetrafluoroborate or hexafluorophosphate anions (again with 2 : 1 metal-to-ligand stoichiometry) at room temperature gave silver complexes with a 1 : 2 (5 and 6) or a 1 : 1 metal-to-ligand ratio (7).The outcome of these latter reactions could be subtly aVected by a change in solvents. For BF4 2 as the anion an ethanol–tetrahydrofuran mixture gave the same isostructural complex composition 5 as an acetonitrile–ethanol–methylene chloride or toluene mixture as shown by X-ray powder diffractometry. For PF6 2 as anion the inclusion of acetonitrile in the solvent mixture led to a 1 : 1 metal–ligand compound 7 instead of the 1 : 2 complex 6.All compounds were obtained in yields above 50%. Characterization was mainly based on X-ray diVraction studies. The metal–ligand co-ordination modes elucidated from single-crystal structure determinations are depicted in Figs. 1, N H2N(O)C N C(O)NH2 Crude product (F3CCO)2O pyridine dioxane P4O 0.2 mbar 200 °C N NC N CN (1) Scheme 1 N N NC CN AgNO3 ethanol 95 °C to RT L 1[Ag(NO3)(µ-L)] 3 ¥ 1[Ag(CF3SO3)(µ-L)] 4 Ag(CF3SO3) toluene 95 °C to RT AgBF4 [Ag(L)2]BF4 5 ethanol/THF or CH3CN/ethanol/ CH2Cl2(toluene) AgPF6 ethanol/THF or ethanol/CH2Cl2/ toluene [Ag(L)2]PF6 6 CH3CN/ethanol/ toluene AgPF6 2[Ag(µ-L)]PF6 · 1/2 C6H5Me 7 ¥ ¥J.Chem. Soc., Dalton Trans., 1999, 183–190 185 3, 5, and 7 for the 1-D co-ordination polymers 3 and 4, the bis-chelate complexes 5 and 6, and the 2-D framework 7, respectively. The structural studies revealed that the anions Fig. 1 Section of the one-dimensional co-ordination polymer of 1 •[Ag(NO3)(m-L)] 3. NO3 2 and CF3SO3 2 in 3 and 4, respectively, still co-ordinate to a metal center with one of the oxygen atoms (Figs. 1 to 4). They serve as terminal ligands and occupy one position in the distorted tetrahedral co-ordination sphere of the silver ions. At the same time, the dicyanobipyridine ligand chelates a silver atom in 3 and 4 through the bipyridine moiety and bridges to a neighboring silver center through one of the exodentate cyano groups.Hence, the silver co-ordination sphere consists of an oxygen atom, two bipyridine nitrogen atoms and a cyano nitrogen atom. The planes of the two pyridine rings within a bipyridine ligand deviate by 9.1(1) (3) and 16.9(3)8 (4) from coplanarity. The potentially tetradentate dicyanobipyridine group functions as a tridentate ligand only; the other cyano group is not involved in metal co-ordination even though a twofold excess of metal over ligand has been oVered during the reaction.The bridging action of the ligand L gives rise to one-dimensional co-ordination polymers, • 1 [Ag(NO3)(m-L)] 3 and • 1 [Ag(CF3SO3)(m-L)] 4, whose metal–ligand arrangement is depicted in Figs. 1 and 3, respectively. While the chain in 4 is oriented rather straight with the metal and bipyridine ligands lying all in one plane, it is noteworthy that the strand for the silver nitrate complex 3 assumes a 21-helical conformation.These chain conformations together with the packing of neighboring strands are further illustrated in Figs. 2 and 4 with the help of stereoplots. The chains run parallel in the Fig. 2 (a) Stereoplot of the chain structure of 1 •[Ag(NO3)(m-L)] 3 illustrating the helical nature and the intertwining of neighboring 21 helices (view along a) and (b) schematic representation of the interdigitation of adjacent strands in 3.186 J. Chem. Soc., Dalton Trans., 1999, 183–190 case of 4.For 3 neighboring strands are of opposite helicity and interlock or interdigitate as is schematically depicted in Fig. 2(b). Bipyridine ligands from adjacent strands mutually intrude into the openings within the chain. The interdigitated bipyridine moieties form p–p stacks with an interplane distance of 3.47 Å. In the orientation of neighboring chains a weakly bridging mode of the NO3 2 and CF3SO3 2 anions may play a role. Interchain non-bonding Ag ? ? ? O contacts are 3.001 Å (to O1) in 3 and 3.370 and 3.590 Å (to O2 and O3, respectively) in 4.In addition, an interchain silver–pyridine or electrostatic Fig. 3 Metal–ligand arrangement in a segment of the one-dimensional co-ordination polymer of 1 •[Ag(CF3SO3)(m-L)] 4. cation p contact might play a small role in 3, as the Ag ? ? ?C distances are 3.497 (to C3), 3.596 (to C4), and 3.716 Å (to C5). Silver is known to have a remarkably high aYnity for some aromatic p-donor systems.16 When silver salts of only weakly co-ordinating anions such as BF4 2 and PF6 2 are employed, as in the isostructural compounds 5 and 6, respectively,8,17 the metal co-ordination Fig. 5 Molecular structures of the bis-chelate complex [AgL2]BF4 5 (shown) and of the isostructural [AgL2]PF6 6. Fig. 4 Stereoplot of the chain structure of 1 •[Ag(CF3SO3)(m-L)] 4 to show the parallel alignment of the chains in contrast to those of 3. View along a. Fig. 6 Stereoscopic partial cell plot of complex 5 to illustrate the packing of the bis-chelate complexes. The BF4 2 anion has been omitted for clarity.View approximately along b.J. Chem. Soc., Dalton Trans., 1999, 183–190 187 sphere is fully constructed from the ligand donor atoms (Figs. 5 and 6). However, only the endodentate bipyridine nitrogen atoms serve as donor atoms towards silver; the exodentate cyano groups are not involved in metal co-ordination even though a twofold molar excess of metal over ligand has again been oVered during the reaction.The results are cationic bischelate complexes of the type [AgL2]1 with BF4 2 (5) and PF6 2 (6) as the anion. The non-involvement of the cyano groups is remarkable in view of their known high aYnity towards Ag1 ions.18 The cyano nitrogen atom is perhaps a somewhat weaker donor atom when compared with a pyridine nitrogen atom. The co-ordination of the latter is definitely enhanced further through the chelate eVect of the bipyridine unit.Two chelating ligands construct a strongly distorted environment, almost halfway between tetrahedral and square planar as is evident from the graphical presentation in Figs. 5 and 6. The interplane angle between the two five-membered chelate rings formed by Ag–N1–C5–C6–N2 and their symmetry equivalent atoms is 55.34(5)8 for 5 and 56.31(5)8 for 6. The origin of this distortion is not clearly apparent as the nearest non-co-ordinating atoms are fluorine atoms, which are, however, 3.12 (5) and 3.16 Å (6) away.The two pyridine rings of the bipyridine ligand remain essentially coplanar to within 38 for 5 or 58 for 6 (based on the torsion angles N1–C5–C6–N2 and C4–C5–C6–C7). A stereoscopic cell plot of 5 in Fig. 6 serves to illustrate the packing of Fig. 7 Section of the two-dimensional framework of 2 •[Ag(m-L)]PF6? 1– 2C6H5Me 7. View along c. The toluene molecule and two of the three crystallographically diVerent PF6 2 anions are not shown for clarity (see Fig. 8 for these remaining moieties and Fig. 9 for the complete ensemble). Owing to space requirements the ligand is not fully labelled. Symmetry equivalent positions: 22 = 2y 1 1, x 2 y 2 1, z; 23 = 2x 1 y 1 1, 2x 1 1, z; 27 = 2x 1 1, 2y 1 1, 2z. Fig. 8 The toluene–PF6 layer in the crystal structure of 2 •[Ag(m-L)]- PF6?1– 2C6H5Me 7 which contains two of the three crystallographically diVerent PF6 2 sites. One of these anions P3 sits on a special position and is disordered. View along c as in Fig. 7. the ionic bis-chelate complexes through a bipyridine p–p interaction of neighboring molecules with an interplane distance of 3.76 Å. The working hypothesis that the co-ordination of the exodentate cyano nitrogen atoms would be exercized only when the simultaneous endodentate co-ordination of two chelating bipyridine moieties was not possible, was proven wrong with the structure elucidation of complex 7. In this two-dimensional co-ordination polymer of formula 2 •[Ag(m-L)]PF6?��� C6H5Me the dicyanobipyridine ligand chelates a silver ion and bridges to two other metal centers with both of the exodentate cyano groups (Fig. 7). Two types of C3-symmetrical triangular openings are thus created in this framework. In the larger ones one of the three crystallographically diVerent PF6 anions is partly immersed. The other two PF6 anion sites lie within a layer together with the toluene solvent molecules (Fig. 8). The metal– ligand layer (A, together with one PF6) and the toluene–PF6 layer (B) are stacked along the c direction in a .. . BAABAA. . . sequence as is illustrated in Fig. 9. Clearly, a silver–toluene or electrostatic cation p contact is present in 7, as rather short Ag ? ? ? C distances of 2.815 (to C18) and 2.830 Å (to C17) are encountered.16 The remaining silver–toluene contacts are 3.381 (to C16), 3.771 (to C15), 3.769 (to C14), and 3.335 Å (to C13). The two pyridine rings are strongly twisted by 21.0(1)8 in 7, more than in the other compounds 3–6.The metal environment is again almost halfway between tetrahedral and square planar. The interplane angle between the five-membered chelate ring and the plane formed by the cyano nitrogen atoms with the silver center is 25.5(2)8. Selected bond distances and angles for compounds 3–6 are summarized in Table 1. Conclusion In the ambidentate ligand 5,59-dicyano-2,29-bipyridine (L) both the bipyridine nitrogen and the exodentate cyano nitrogen atoms can function as donors towards a silver metal center.The choice of metal co-ordination was found to depend on the counter anion 8,19 or the solvent of crystallization. When a coordinating anion was present in the silver co-ordination sphere L acted as a tridentate ligand, chelating through the bipyridine moiety and bridging through one of the cyano groups. With non-co-ordinating anions the silver co-ordination sphere was solely constructed from the ligand nitrogen donors.Either the formation of bis-chelate silver complexes through bisbipyridine nitrogen co-ordination be observed with L as a bidentate ligand, or, with a slight change in the solvent mixture for crystallization, L could also become tetradentate Fig. 9 Partial cell plot of 2 •[Ag(m-L)]PF6?1– 2C6H5Me 7 viewed along the ab plane to show the . . . BAABAA. . . sequence of the metal–ligand (A) and toluene–PF6 (B) layers which were separately depicted in Figs. 7 and 8.188 J. Chem. Soc., Dalton Trans., 1999, 183–190 Table 1 Selected bond distances (Å) and angles (8) for complexes 3–7 Compound Ag1–N1bipy Ag1–N2bipy Ag1–N3CN Ag1–N4CN Ag1–O1 N3–C11 N4–C12 1 •[Ag(NO3)(m-L)] 3 2.339(2) 2.453(2) a: 2.425(3) 2.371(2) 1.143(4) 1.148(4) 1 •[Ag(CF3SO3)(m-5)] 4 2.349(6) 2.322(4) c: 2.156(5) 2.689(5) 1.139(7) 1.116(8) [AgL2]BF4 5 2.356(2) 2.312(2) 1.139(4) 1.137(4) [AgL2]PF6 6 2.325(2) 2.378(3) 1.140(5) 1.144(5) 2 •[Ag(m-L)]PF6?1– 2C6H5Me 7 2.377(6) 2.444(6) g: 2.375(7) h: 2.294(7) 1.134(10) 1.146(10) Within the anions N1–Ag1–N2 N1–Ag1–O1 N2–Ag1–O1 N1–Ag1–N4 N2–Ag1–N4 O1–Ag1–N4 C12–N4–Ag1 X–O1–Ag1 O1–N5 1.277(3) O2–N5 1.236(3) O3–N5 1.240(3) 68.42(7) 148.69(8) 129.38(8) a: 106.44(8) a: 90.32(8) a: 99.54(9) b: 148.4(2)1 X = N5; 103.0(2) O1–S1 1.438(5) O2–S1 1.438(5) O3–S1 1.430(5) 70.6(2) 105.5(2) 118.3(2) c: 129.2(2) c: 144.3(2) c: 87.3(2) d: 168.3(6) X = S1: 110.8(3) N1–Ag1–N2 N1–Ag1–N1 N2–Ag1–N2 N1–Ag1–N2 N1–Ag1–N3 N1–Ag1–N4 N2–Ag1–N3 N2–Ag1–N4 N3f–Ag1–N4g B1–F1 1.389(4) B1–F2 1.374(4) 71.12(8) e: 136.5(1) e: 165.7(1) e: 114.57(8) P1–F1 1.596(2) P1–F2 1.599(3) P1–F3 1.596(2) 70.75(9) f: 170.5(1) f: 135.3(1) f: 113.12(9) P1–F 1.539(7)–1.569(9) P2–F 1.576(10)–1.601(11) P3–F 1.40(4)–1.54(4) 68.38(19) g: 88.4(2) h: 164.6(3) g: 144.9(3) h: 101.7(3) 94.5(3) Symmetry transformations apply to the last atom in the bond or angle definition if not assigned otherwise: a = 2x 1 0.5, y 2 0.5, 2z 1 0.5; b = 2x 1 0.5, y 1 0.5, 2z 1 0.5; c = 2x 1 1, y 1 0.5, 2z 1 1.5; d = 2x 1 1, y 2 0.5, 2z 1 1.5; e = 2x, y, 2z 1 0.5; f = 2x 1 1, y, 2z 1 1.5; g = 2y 1 1, x 2 y 2 1, z = _2 in Fig. 7; h = 2x 1 y 1 1, 2x 1 1, z = _3 in Fig. 7. utilizing all four nitrogen donor atoms in chelating and bridging co-ordination between three metal centers. Pyridine p–p interactions and silver–pyridine or –toluene cation p contacts were controlling factors in the non-bonded crystal organization. Experimental The NMR spectra were collected on a Varian O-300 spectrometer (300.0 MHz for 1H, 75.4 MHz for 13C) and calibrated against the solvent signal (d8-THF: 1H, d 1.73; 13C, d 25.2), IR spectra on a Perkin-Elmer 783 spectrophotometer as KBr disks or as Nujol mulls.Elemental analyses were carried out with a Perkin-Elmer Elemental Analyzer E 240 C. X-Ray powder diVractograms were obtained with a Siemens powder diVractometer D5000 using Cu-Ka radiation. All crystallizations of the silver complexes were carried out in the dark.Preparations 2,29-Bipyridine-5,59-dicarboxamide. A mixture of 3.0 g of diethyl 2,29-bipyridine-5,59-dicarboxylate, 100 ml of ethanol and 100 ml of ethylene glycol was saturated with ammonia and heated in a sealed round bottom flask in an oil-bath at 95 8C for 48 h. The precipitate formed was collected and washed with hot ethanol and ethylene glycol. 1.9 g (79%) of 2,29-bipyridine-5,59-dicarboxamide was obtained, mp >280 8C (lit.15 >310 8C).IR: 3375s, 3170s, 1660s, 1634s, 1599s, 1548m, 1480w, 1410s, 1370m, 1285w, 1252m, 1165w, 1132m, 1118w, 1055w, 1028m, 955w, 860m, 810w, 790m, 760w, 720m, 665m, 659m, 638m, 600w and 535w cm21. 5,59-Dicyano-2,29-bipyridine (L). This compound was prepared by two methods. Literature method.15 2,29-Bipyridine-5,59-dicarboxamide (0.2 g, 0.8 mmol) and 0.5 g (1.7 mmol) of P4O10 were placed into a sublimator and kept at 0.2 mbar/300 8C until the sublimation had ceased. The crude product which easily absorbs water from the air was resublimed to obtain 0.1 g of a colorless solid.This was repurified with 0.2 g of P4O10 in a sublimator at 0.2 mbar/ 300 8C followed by resublimation to give 0.05 g of L (29% yield), mp 275.9–276.6 8C (lit. 269–271,15 284–285 8C14). IR: 3420w, 3070w, 2240s, 1985w, 1898w, 1796w, 1720s, 1597s, 1540m, 1468s, 1373s, 1292m, 1240s, 1170w, 1130w, 1053w, 1030s, 948w, 850s, 795w, 776w, 751m, 726m, 652m and 554m cm21. Modified method.Trifluoroacetic anhydride (2.5 ml, 18.4 mmol) was added dropwise to a stirred ice-cooled suspension of 2,29-bipyridine-5,59-dicarboxamide (2.0 g, 8.4 mmol) in anhydrous 1,4-dioxane (150 ml) and anhydrous pyridine (1.5 ml, 18.4 mmol). Over the period of the addition the temperature was kept below 5 8C. The reaction mixture was then allowed to warm to room temperature and stirred for 10 h. Then 100 ml of distilled water were added, the solid product was removed by filtration and washed with water to obtain 1.5 g of crude product.A 0.2 g amount of this was heated together with 0.5 g of P4O10 in a sublimator at 0.2 mbar/180 8C until sublimation had ceased. The solid was purified by resublimation to obtain 0.12 g of a colorless solid (L) (43% yield), mp 275.4–276.2 8C. The IR spectrum was identical to that of the above sample. 1H NMR (d8-THF): d 8.34 (dd, 2 H, H4, H49, J = 8.3, 2.1), 8.57 (dd, 2 H, H3, H39, J = 8.2, 0.8 Hz) and 8.9 (br, 2 H, H6, H69). 13C NMR (d8-THF): d 111.63 (C5, C59), 117.49 (CN), 122.38 (C3, C39), 142.33 (C4, C49), 153.40 (C6, C69) and 157.75 (C2, C29). (Ï-5,59-Dicyano-2,29-bipyridine)nitratosilver(I), 1 •[Ag(NO3)- (Ï-L)] 3. In a 50 ml round bottom flask an ethanolic solution (10 ml) of L (21 mg, 0.10 mmol) was added to an ethanolic solution (15 ml) of silver nitrate (34 mg, 0.20 mmol). A yellow precipitate immediately formed. The flask was sealed and heated to 95 8C for 24 h. The reaction mixture was then cooled to room temperature at a rate of 1 8C h21.Well formed yellow rod-like crystals were produced, collected by filtration, washed with water and ethanol and dried under vacuum. Yield: 28 mg (76%, based on L) (Found: C, 38.07; H, 1.56; N, 17.92. Calc. for C12H6AgN5O3: C, 38.30; H, 1.60; N, 18.60%). IR: 3440m, 3110w, 3062w, 3030w, 2240m, 1725w, 1598s, 1540w, 1478s, 1468m, 1387s, 1316m, 1240m, 1249w, 1030m, 849m, 735m, 651s and 555w cm21. (Ï-5,59-Dicyano-2,29-bipyridine)(trifluoromethanesulfonato)- silver(I), 1 •[Ag(CF3SO3)(Ï-L)] 4.In a 50 ml round bottom flask a solution of Ag(CF3SO3) (56 mg, 0.22 mmol) in 5 ml of toluene was added to 15 ml of a toluene solution of L (21 mg,J. Chem. Soc., Dalton Trans., 1999, 183–190 189 0.1 mmol). A white precipitate immediately formed. The flask was sealed and heated to 95 8C for 24 h, followed by cooling to room temperature at 1 8C h21. The well formed colorless to pale green crystals were collected by filtration, washed with ethanol and dried under vacuum.Yield 31 mg (67%) (Found: C, 33.37; H, 1.26; N, 11.86. Calc. for C13H6AgF3N4O3S: C, 33.69; H, 1.29; N, 12.10%). IR: 3440m, 3120w, 3070w, 3138w, 2270w, 2240m, 1598s, 1540m, 1480m, 1468s, 1374m, 1260s, 1240m, 1188w, 1160s, 1035s, 1030s, 945w, 850s, 705m, 650m, 634m, 580w, 555m and 520m cm21. Bis(5,59-dicyano-2,29-bipyridine)silver(I) tetrafluoroborate, [AgL2]BF4 5. A solution of AgBF4 (21 mg, 0.10 mmol) in 10 ml of ethanol was carefully overlayered in a test-tube with a solution of L (10 mg, 0.05 mmol) in 10 ml of tetrahydrofuran.After 10 d at room temperature, well formed orange crystals had appeared at the boundary between ethanol and THF. They were collected, washed with water and ethanol and dried under vacuum. Yield 8 mg (66% based on L) (Found: C, 47.40; H, 1.97; N, 18.38. Calc. for C24H12AgBF4N8: C, 47.54; H, 1.98; N, 18.48%). IR: 3440m, 3124w, 3064w, 3235w, 2239m, 1725w, 1598s, 1560w, 1540w, 1478s, 1467m, 1388s, 1376m, 1320m, 1241m, 1126m, 1088m, 1070s, 1050s, 1030s, 1000m, 946w, 938w, 869m, 850w, 735m, 670w, 650w, 560w and 522w cm21.When a solution of AgBF4 (10 mg, 0.05 mmol) in 0.5 ml of acetonitrile and 4 ml of ethanol was carefully overlayered in a test-tube with a solution of L (21 mg, 0.10 mmol) in 10 ml of dichloromethane (or toluene) orange crystals were obtained after 5 d. Yield 15 (18) mg [49% (58%)]. The crystals were identified as complex 5 based on an identical IR spectrum.Furthermore, they were shown to be isotypic from their X-ray powder diVractograms which in addition matched the calculated pattern from the single crystal data. Bis(5,59-dicyano-2,29-bipyridine)silver(I) hexafluorophosphate, [AgL2]PF6 6. A solution of AgPF6 (28 mg, 0.11 mmol) in 10 ml of ethanol was carefully overlayered in a test-tube with a solution of L (10 mg, 0.05 mmol) in 10 ml of tetrahydrofuran. After 12 d at room temperature, the well formed orange crystals were collected, washed with water and ethanol and dried under vacuum.Yield 19 mg (57% based on L) (Found: C, 42.81; H, 1.59; N, 16.51. Calc. for C24H12AgF6N8P: C, 43.31; H, 1.80; N, 16.85%). IR: 3435m, 3139w, 3064w, 3036w, 2238m, 1728w, 1600s, 1560w, 1540w, 1480s, 1466m, 1388s, 1380m, 1323m, 1250m, 1150w, 1033m, 947w, 860m, 850w, 830m, 788w, 733w, 670w, 650w and 562w cm21. Slow concentration of a mixture of solutions of AgPF6 in ethanol and of L in THF (or dichloromethane and toluene) in the mole ratio of 1 : 1 (or 2 : 1) also gave complex 6, with the yield being about 57%. The identity was based on IR spectroscopy and X-ray powder diVractometry. (Ï3-5,59-Dicyano-2,29-bipyridine)silver(I) hexafluorophosphatehemitoluene solvate, 2 •[Ag(Ï3-L)]PF6?1–2 C6H5Me 7.A solution of 27 mg (0.11 mmol) of AgPF6 in a mixture of 1 ml of acetonitrile and 2 ml of ethanol was overlayered in a test-tube with a solution of 10 mg (0.05 mmol) of L in 6 ml of toluene.After 8 d at room temperature (in the dark) pale yellow crystals had formed. Yield 16 mg (64% based on L) (Found: C, 36.66; H, 1.93; N, 11.40. Calc. for C15.5H10AgF6N4P: C, 36.8; H, 1.98; N, 11.90%). IR: 3440m, 3108w, 3070w, 2240m, 1730w, 1598s, 1550w, 1540s, 1478s, 1467s, 1374m, 1280w, 1240s, 1088s, 1054w, 1030s, 950m, 850s (br), 776m, 734m, 695m, 650m, 565s and 555m cm21. Even when stored in the dark, compound 7 slowly turned dark and appeared to be more sensitive to decomposition than the other four complexes 3–6.Structure determinations Data were collected on a Bruker Smart CCD diVractometer with Mo-Ka radiation (l = 0.71073 Å) and the use of a graphite monochromator. The crystal specimens were cooled to 173(2) K. Structure solution was performed by direct methods (SHELXL 97).20 Refinement: full-matrix least squares on F 2 (SHELXL 97); all non-hydrogen positions found and refined with anisotropic thermal parameters. The hydrogen atoms of complexes 3, 5 and 6 were found and refined, including the thermal parameter.Calculated hydrogen positions were added in the structures of 4 and 7, refined as riding atoms on the bonded carbon atom position. With respect to data quality it should be noted that the crystal of 4 was very small. The refinement of the heavily disordered fluorine atoms in the third hexafluorophosphate anion of 7 (P3, cf. Fig. 8) is a rough approximation, the electron density related to the fluorine Table 2 Crystal data for compounds 3–7 Formula M Crystal system Space group Crystal size/mm 2q range/8 h; k; l range a/Å b/Å c/Å b/8 V/Å3 Z Dc/g cm23 F(000) m/cm21 Measured reflections Unique reflections (Rint) Observed reflections [I > 2s(I )] Parameters refined Dr/e Å23 a R1; wR2 [I > 2s(I )] (all reflections) 3 C12H6AgN5O3 376.09 Monoclinic P21/n 0.4 × 0.2 × 0.1 4–62.1 210, 11; 210, 7; 229, 24 8.2230(2) 7.5328(2) 20.3896(5) 93.308(1) 1260.87(5) 4 1.981 736 16.17 9319 3703 (0.0586) 3269 214 0.537; 21.361 0.0337; 0.0796 0.0403; 0.0839 4 C13H6AgF3N4O3S 463.15 Monoclinic P21/c 0.15 × 0.1 × 0.02 4.3–57.8 211, 12; 25, 21; 29, 12 9.4946(5) 15.8010(8) 10.3381(5) 92.242(2) 1549.78(14) 4 1.985 904 14.91 5664 2813 (0.0836) 1634 226 0.616; 20.960 0.0522; 0.0874 0.1188; 0.1094 5 C24H12AgBF4N8 607.10 Monoclinic C2/c 0.3 × 0.15 × 0.1 4.0–62.3 217, 31; 210, 9; 221, 22 21.9430(3) 7.5298(1) 15.7431(2) 112.676(1) 2400.10(5) 4 1.680 1200 9.02 7335 3420 (0.0416) 2561 197 0.562; 20.808 0.0440; 0.0925 0.0693; 0.1035 6 C24H12AgF6N8P 665.26 Monoclinic C2/c 0.3 × 0.2 × 0.05 4.1–57.5 228, 25; 24, 10; 210, 10 21.8760(1) 8.2210(2) 15.8848(3) 115.277(1) 2583.24(8) 4 1.711 1312 9.17 4895 2649 (0.0298) 2286 206 0.369; 20.593 0.0384; 0.0852 0.0486; 0.0907 7 C15.5H10AgF6N4P 505.11 Hexagonal P63/m 0.4 × 0.3 × 0.3 2.6–60.4 224, 17; 28, 24; 227, 9 17.8017(3) 17.8017(1) 19.6142(1) 90 5383.0(1) 12 1.870 2964 12.80 22491 5094 (0.0538) 3491 277 1.694; 22.171 0.0753; 0.1882 0.1104; 0.2037 a Largest diVerence peak and hole.190 J.Chem. 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