Crystal synthesis using secondary and dative coordinate bonding: 4,4�-bipyridyl adducts of arylbismuth dihalides Sîan C. James, Nicholas C. Norman, A. Guy Orpen and Jonathan Starbuck University of Bristol, School of Chemistry, Cantock’s Close, Bristol, UK BS8 1TS. E-mail: guy.orpen@bristol.ac.uk Received 8th March 2000, Accepted 30th March 2000, Published 12th April 2000 Reaction between BiX2Ph (X = Cl or I) and 4,4�-bipy afforded crystals of complexes trans-[BiX2Ph(4,4�-bipy)]n as solvates in which an anticipated combination of dative (Bi–bipy) and secondary bonding (Bi···X) leads to a controlled polymeric structure. Although there are many examples of coordination polymers containing transition metals with 4,4�-bipy like those noted above, in contrast only two examples exist containing a main group metal, namely [Sn(4,4�-bipy) Me3]n·n{N(SO2Me)2} (MeCN) [N(SO2Me)2 = dimesylamide],10 where the tin is approximately trigonal bipyramidal with axial nitrogens, and [Sn(4,4�-bipy)Cl2Me2]n.11 In both cases linear [Sn(4,4�-bipy)]n chains are formed.Since the Lewis acidity of bismuth(III) halides and their coordination chemistry with two-electron donor ligands is now well established,12 an analogous chemistry with bismuth is to be expected. In monoarylbismuth dihalides, BiX2Ar, and the mono and bis-ligand complexes derived from them, [BiX2Ar(L)] and [BiX2Ar(L)2], the bismuth centre usually has a five-coordinate, square-based pyramidal geometry with the aryl group in the apical position. Examples include polymeric BiBr2Ph, a small unit of which is shown in A,13 [BiX2Ph(thf)] (X = Cl, Br, I) for which a one-dimensional structure is found (B),14 [BiBr2Ph(OPPh3)] which is dimeric (C)15 and the bis-ligand complexes [BiBr2Ph(dmpu)2] (dmpu = N,N�-dimethylpropylene urea) (D), where the ligands adopt a cis-configuration,15 and [BiCl2Ph(4-Mepy)2] (4-Mepy = 4-methylpyridine) (E) where the ligands are trans.12 In situations where the ligand L in the mono adducts [BiX2Ar(L)] is a halide anion, dimeric species of the general formula [Bi2X6Ph2]2– are observed for which the structures [NBun4]2[Bi2Br6Ph2] (F)14a and [NEt4]2[Bi2I6Ph2] (G)14b are typical.For the bis-ligand complexes [BiX2Ar(L)2], the reasons why some have ligands L mutually cis whereas others are trans are discussed in ref.12. Whatever the causes, pyridine ligands seem to have a clear preference for the trans geometry.12 We reasoned, therefore, that by employing 4,4�-bipy, one-dimensional polymeric structures would result from a 1 : 1 Bi : bipy stoichiometry. This expectation was borne out by the experimental results communicated herein. Further one would expect that these chains would cross-link through the (rather weak and so less reliable) Bi···X secondary bonding ability of the bismuth centre, approximately trans to the aryl group, as seen in many of the structures described in ref. 12. We are not aware of any previous examples of arylbismuth(III) halide structures with 4,4�-bipy as a ligand although a number of studies have been carried out using 2,2�- bipyridyl.16 Introduction Modern crystal engineering strategies have focused on the use of directional interactions such as hydrogen bonding1 and dative coordinate bonding2 to control the aggregation of molecular species.We have recently3 indicated on the basis of a data mining study that the secondary bonding capability of the heavy p-block elements, as defined by Alcock,4 may be a useful alternative or complement to these well established classes of interaction in this context. The work of Mitzi and others5 has already demonstrated the potentially important properties that such solids might possess. The strategy of combining known metal coordination environments with multifunctional exodentate ligands has led to the preparation of a wide variety of crystalline architectures.2,6 The networks in these solids have typically been built around late d-block elements (Groups 8–12) and linear bifunctional 'spacer' ligands such as 4,4�-bipyridine (bipy).For example, with a 1 : 1 stoichiometry of metal to 4,4�-bipy ligand, in general each metal is connected by two bridging trans-related 4,4�-bipy ligands to form onedimensional [M(4,4�-bipy)]n chains. Examples of such structures containing neutral chains include [Fe(4,4�- bipy)(ClO4)2(H2O)2]n·n(4,4�-bipy),6a [Co(4,4�-bipy)(NCS)2 (H2O)2]n·n(4,4�-bipy),6b [Ni(4,4�-bipy)(C5H9OS2)2]n·2nCCl4,6c (C5H9OS2 = n-butylxanthate), [Cu(4,4�-bipy)(BF4)2(H2O)2]n ·n(4,4�-bipy),6d [Cu(4,4�-bipy)(2,2�-bipy)(ClO4)2]n,6e and [Cd(4,4�-bipy)(C4H7OS2)2]n (C4H7OS2 = iso-propylxanthate).6f The structures of selected Group 8–12 dihalides with 1 equivalent of 4,4�-bipy are slightly more complex.For species of general formula [MX2(4,4�-bipy)]n (M = Fe, X = Cl;7a M = Co, X = Cl;7a M = Ni, X = Cl, Br;7b M = Cu, X = Cl, Br;7b M = Cd, X = I;7c M = Hg, X = Br7d) the bipy ligand again acts as a linear bifunctional bridge forming [M(4,4�-bipy)]n chains. However the remaining coordination sites are occupied by bridging halide ions which link the M centres in neighbouring chains via double bridges to form extended two-dimensional layers. One example exists in the Cambridge Structural Database8 (CSD) of a structure with a 1 : 1 M : bipy stoichiometry in which there is a cis-arrangement, yielding, as a consequence, a square motif, viz.[Re(4,4�- bipy)Cl(CO)3]4·0.33(Me2CO).9 In most of the structures of this type, it is notable that an octahedral geometry is adopted at the metal centre. DOI: 10.1039/b001874k CrystEngComm, 2000, 10Br Ph Ph Bi Bi Br Br Br X Br Br Br Bi Bi Br L Br PhC, L = OPPh Ph Br Br Bi Bi Br Br Br Ph FA B, X = Cl, Br, I; L = thf Ph Br L 3 Br Ph Br L Br 2¡© N Ph Cl I I X Results and discussion The reaction between BiCl2Ph and 4,4¢¥-bipy in the ratio 1 : 1 afforded crystals of the complex [BiCl2Ph(4,4¢¥-bipy)]n (1) as a hemi-hexane solvate (see Experimental section). The primary structure (see Fig. 1), as expected, comprises onedimensional polymeric chains which extend along the crystal <110> direction.In these chains the bismuth centres adopt five-coordinate, square-based pyramidal geometries with apical phenyls and mutually trans pairs of chlorines and 4,4¢¥-bipy ligands [Cl¡©Bi¡©Cl = 177.0(2), N¡©Bi¡© N = 173.0(7)¡Æ]. There is a twist in the central bond of the bridging 4,4¢¥-bipy ligand of 18.7¡Æ but the individual pyridyl ring planes lie close to the plane of the BiCl2N moiety. Additional highly asymmetric (and by implication weak) secondary bismuth¡©chlorine bonds [Bi¡�¡�¡�Cl = 3.582(7) A, cf. Bi¡©Cl = 2.717(6) A] approximately trans to the phenyl groups [Cl¡�¡�¡�Bi¡©C = 154.2(2)¡Æ] are present between chains. These interactions are of similar length to those observed in other structures of arylbismuth halide pyridine complexes described in ref.12. Occluded within the structure, in channels walled by phenyl groups, are disordered hexane molecules of crystallisation. The apical phenyl groups were also disordered with two different orientations corresponding to the two different positions of the disordered hexane guest molecules, in the ratio 55 : 45. There are relatively short face¡©edge C¡©H¡�¡�¡�¥� interactions involving the apical phenyl groups in the <100> direction (2.53¡©3.03 A for C¡©H¡�¡�¡�centroid of Ph ring, if the two disordered parts are considered to alternate along this direction). Additional weak C¡©H¡�¡�¡�Cl inter-chain X L XBi BiX L X L Bi L D, L = dmpu I Ph PhX Bi I X Bi N interactions are present between aryl hydrogens H(8), H(10), H(13), H(15) of the bipyridyl ligand and Cl(1), Cl(2) parallel to the (001) plane (chelating C¡©H¡�¡�¡�Cl dist crystals 2 with a structure broadly similar to that of 1 except that the solvent of crystallisation in 1 had been replaced by molecules of 4,4¢¥-bipy to give [BiI2Ph(4,4¢¥- bipy)]n¡�0.5n(4,4¢¥-bipy) (2) (see Fig.2). Once again the primary structure comprises a one-dimensional polymeric chain, in this case along the <¡©101> direction. The bismuth centres adopt five-coordinate, square-based pyramidal geometries with apical phenyls and mutually trans pairs of iodines and bridging 4,4¢¥-bipy ligands [I(1)¡©Bi(1)¡© I(2) = 179.29(3), N(1)¡©Bi(1)¡©N(4) = 168.7(4); I(3)¡©Bi(2)¡© I(4) = 177.11(4), N(2)¡©Bi(2)¡©N(3) = 177.7(4)¡Æ].¢Ó Highly asymmetric secondary bismuth¡©iodine bonds crosslink the chains [Bi(1)¡�¡�¡�I(4) = 3.9091(13), cf.Bi(2)¡© I(4) = 3.0698(14) A; Bi(2)¡�¡�¡�I(2) = 3.8708(13), cf. Bi(1)¡© I(2) = 3.0857(14) A] approximately trans to the phenyl groups [I(4)¡�¡�¡�Bi(1)¡©C(1) = 156.2(3); I(2)¡�¡�¡�Bi(2)¡©C(7) = 157.3(3)¡Æ]. In contrast to 1, the occluded guest molecules, G1, X = Cl; 2, X = I L X X Bi Bi X L L Ph I Bi Bi2¡© Ph X Bi Cl E, L = 4-Mepy N N INFig. 1 A portion of the crystal structure of 1. Click image or here to access a 3D representation.here 4,4¢¥-bipy, in 2 are relatively well ordered and a twist angle of 32.7¡Æ within the bipy is observed. The increased ordering of the guest molecule in 2 is presumably due to the stronger interactions formed by the occluded 4,4¢¥-bipy molecules within the channels compared with interactions involving the hexane molecules. This is consistent with relatively short C¡©H¡�¡�¡�¥� interactions involving the apical phenyl groups (2.95¡©3.07 A for C¡©H¡�¡�¡�centroids), and a short C¡©H¡�¡�¡�N interaction (2.48 A) formed between adjacent 4,4¢¥-bipy guest molecules, leading to a 'chain' of 4,4¢¥-bipy molecules in the <100> direction. In addition, also in the <100> direction short C¡©H¡�¡�¡�¥� interactions occur between adjacent apical phenyl groups, once again forming an infinite chain [C(5)¡©H(5)¡�¡�¡�centroid C(7)¡©C(12) = 2.95 A; C(2)¡©H(2)¡�¡�¡�centroid C(7)¡©C(12) = 2.95 A].Additional C¡© H¡�¡�¡�I inter-chain interactions are present between the hydrogens of the bipyridyl ligand and I(1) and I(4) (C¡©H¡�¡�¡�I in the range 3.06¡©3.13 A), although in 2 there is only one interaction per iodine (cf. the chelating interactions present in 1). Fig. 2 A portion of the crystal structure of 2. Click image or here to access a 3D representation. The volumes occupied by the occluded guest molecules were calculated using the CERIUS2 software.17 For 1 the volume occupied by the structure (including hexane guest molecules) accounts for between 69.9¡©71.5% of the total unit cell volume, depending on the site occupied by the disordered hexane molecule.For 2 the corresponding value is 68.8%. In the absence of the guest molecules (see Fig. 3), the calculated occupied volumes are 58.4% for 1 and 55.7% for 2. This observation, combined with the fact that the hexane guest is less tightly bound in the channels than the 4,4¢¥-bipy guest would suggest there is more chance of guest exchange or removal for 1 than for 2. When BiBr2Ph was employed, the crystals isolated from EtOh¡©2-picoline solution revealed a more complicated structure with the formula [BiBr2Ph(4,4 bipy)][BiBr2Ph2(4,4 ELS\ @>SLF+@3) (2-pic = 2-picoline). that the solid state structure of compound 3 incorporatesFig. 3 A portion of the crystal structure of 2 with occluded 4,4¢¥-bipy omitted to show channels occupied by guest molecules.Click image or here to access a 3D representation. n neutral one-dimensional coordination polymers analogous to those found in 1 and 2, which again dimerise through secondary bismuth¡©bromine bonds, but also contains the one dimensional anionic chain {[BiBr2Ph2(4,4 in which the bismuth centres have a six-coordinate, octahedral geometry with mutually trans pairs of bromines, phenyls and 4,4 ELS\ OLJDQGV 7KH countercation is protonated 2-picoline. A polymeric anion of this type with octahedral bismuth is unprecedented. Ph Ph Br Br N N Bi Bi N Br Br Ph Ph ELS\ @¡©} N N1 2 C19H20BiCl2N2 C21H17BiI2N3 556.25 774.16 Triclinic Monoclinic P 1 (2) P21/c (14) 2 8 9.4377(17) 9.5403(10) 11.733(3) 98.98(2) 108.264(15) 100.458(18) 960.5(3) 123(2) 9.458 10253 4384 0.0407 Conclusions These observations may be summarised as follows: (1) The Lewis acidity of BiCl2Ph and BiI2Ph has been exploited to generate linear chain coordination polymers of bismuth and 4,4¢¥-bipy. Table 1 Crystal data and details of measurements for 1 and 2a Property Formula MSystem Space group (no.) Za/A b/A c/A ¥á/¡Æ ¥â/¡Æ ¥ã/¡Æ U/A3 Temperature/K ¥ì (Mo-K¥á)/mm¡©1 Measured reflections Unique reflections R1 [on F, I > 2 ¥ò (I)] a Click here for full crystallographic data (CCDC no.1350/16). (2) The cross-linking potential of weak secondary Bi¡�¡�¡�halide bonding in these species has afforded a ladder-like dimerisation of these chains.(3) As a consequence of chain dimerisation the phenyl substituents at Bi are all on the same side of the BiX2(¥ì-4,4¢¥-bipy) chain. The phenyl groups then interact to develop the crystal structure through phenyl¡�¡�¡�phenyl edge¡©face (C¡©H¡�¡�¡�¥�) interactions. (4) The resultant structure has channels which accommodate guest molecules (of hexane or 4,4¢¥- bipy) thereby achieving packing efficiencies of ca. 69%. Opportunities for further development of secondary bonding and dative coordinate bonding to yield coordination polymers in this and related chemistry and to exploit the chemistry of the solids so prepared are under active exploration at Bristol.9.663(2) 22.631(5) 20.634(5) 90 100.544(14) 90 4435.9(18) 173(2) 10.743 33577 6939 0.0557Experimental General considerations All reactions were carried out under an atmosphere of dry dinitrogen or argon using standard Schlenk or dry-box techniques and oven-dried glassware. All solvents used were distilled under nitrogen and dried over appropriate drying agents (CaH2 for CH2Cl2, Na for hexanes and Na/benzophenone for thf and Et2O). BiCl3, BiBr3 and BiI3 (99.99%) was procured from Aldrich and generally used without further purification (filtration to remove insoluble BiOX was occasionally necessary). 4,4¢¥-Bipyridyl was also obtained from Aldrich. Arylbismuth halides were prepared according to literature routes.13¡©15 Preparations [BiCl2Ph(4,4¢¥-bipy)]n¡�0.5n(C6H14) (1). A solution of 4,4¢¥-bipyridyl (0.022 g, 0.14 mmol) in 2-picoline was added to a solid sample of BiCl2Ph (0.05 g, 0.14 mmol) and a hexane overlayer was carefully added to the resulting solution.Clear colourless block-like crystals of 1 were obtained over 2 d (0.06 g, 0.11 mmol, yield 77%). C16H13BiCl2N2¡�xC6H14 where x = 0.5 requires C, 41.0; H, 3.6; Cl, 12.8; N, 5.0%. Found: C, 38.3; H, 2.6; Cl, 13.0; N, 5.2% indicating a partial occupancy of the hexane guest where x 0.2. [BiI2Ph(4,4¢¥-bipy)]n¡�0.5n(4,4¢¥-bipy) (2). A solution of 4,4¢¥-bipyridyl (0.015 g, 0.10 mmol) in 2-picoline was added to a solid sample of BiI2Ph (0.05 g, 0.09 mmol) and a hexane overlayer was carefullysis indicated a mixture of products. C16H13BiI2N2¡�xC10H4N2 where x = 0.5 requires C, 32.6; H, 2.2; I, 32.8; N, 5.4%. Found: C, 28.1; H, 3.2; I, 29.3; N, 4.6%. [BiBr2Ph(4,4¢¥-bipy)][BiBr2Ph2(4,4¢¥-bipy)][2-picH] (3). A solution of 4,4¢¥-bipyridyl (0.018 g, 0.12 mmol) in 2- picoline¡©ethanol was added to BiBr2Ph (0.05 g, 0.11 mmol) and a hexane overlayer was carefully added to the resulting solution. Orange crystals of 3 were obtained over a period of 1 week. Satisfactory elemental analysis could not be obtained on a bulk sample. Crystal structure determinations of 1 and 2 Crystals were mounted in inert oil under a stream of argon and transferred to the cold stream of the diffractometer.Crystallographic data for 1 and 2 are presented in Table 1. Measurements were made on a Bruker SMART CCD area diffractometer with Mo-K¥á radiation ( ¥ë = 0.71073 A). Intensities were integrated from several series of exposures, each exposure covering 0.3¡Æ in ¥ø. Absorption corrections were applied, based on multiple and symmetry equivalent measurements. The structures were solved and refined using standard methods.18 Hydrogen atoms were constrained to idealised geometries using a riding model and were assigned isotropic displacement parameters U(H) = 1.2*Uiso(C). References 1 G. R. Desiraju, Chem. Commun., 1997, 1475; J. C.MacDonald and G. M. Whitesides, Acc. Chem Res., 1995, 28, 37; C. B. Aakeroy, Acta Crystallogr., Sect. B, 1997, 53, 569; I. G. Dance, in The Crystal as a Supramolecular Entity, ed. G. R. Desiraju, Perspectives in Supramolecular Chemistry, Wiley, Chichester, vol. 2, 1996; G. R. Desiraju, Angew. Chem., Int. Ed. Engl., 1995, 34, 2311; A. Nangia and G. R. Desiraju, Acta Crystallogr., Sect. A, 1998, 54, 934. 2 S. R. Batten and R. Robson, Angew. Chem., Int. Ed., 1998, 37, 1461; M. J. Zaworotko, Chem. Soc. Rev., 1994, 23, 283; L. Carlucci, G. Ciani, P. Macchi, D. M. Proserpio and S. Rizzato, Chem. Eur. J., 1999, 5, 237; L. Tei, V. Lippolis, A. J. Blake, P. A. Cooke and M. Schroder, Chem. Commun., 1998, 2633; T. Iwamoto, S. Nishikiori, T. Kitazawa and H.Yuge, J. Chem. Soc., Dalton Trans., 1997, 4127. 3 J. Starbuck, N. C. Norman and A. G. Orpen, New J. Chem., 1999, 23, 969. 4 (a) N. W. Alcock, Adv. Inorg. Chem. Radiochem., 1972, 15, 1; (b) N. W. Alcock, Bonding and Structure, Ellis Horwood, Chichester, 1990. 5 D. B. Mitzi, Prog. Inorg. Chem., 1999, 48, 1; L. Sobczyk, R. Jakubas and J. Zaleski, Pol. J. Chem., 1997, 71, 265. 6 (a) L. Carlucci, G. Ciani, D. M. Proserpio and A. Sironi, J. Chem. Soc., Dalton Trans., 1997, 1801; (b) J. Lu, T. Paliwala, S. C. Lim, C. Yu, T. Niu and A. J. Jacobson, Inorg. Chem., 1997, 36, 923; (c) R. W. Gable, B. F. Hoskins and G. Winter, Inorg. Chim. Acta, 1990, 96, 151; (d) A. J. Blake, S. J. Hill, P. Hubberstey and W.-S. Li, J. Chem. Soc., Dalton Trans., 1997, 913; (e) C.Chen, D. Xu, Y. Xu and C. Cheng, Acta Crystallogr., Sect. C, 1992, 48, 1231; (f) B. F. Abrahams, B. F. Hoskins and G. Winter, Aust. J. Chem., 1990, 43, 1759. 7 (a) M. A. Lawandy, X. Huang, R.-J. Wang, J. 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M. M. Hannaway, P. C. Junk, A. M. Lee, B. W. Skelton and A. H. White, Aust. J. Chem., 1998, 51, 331. 17 CERIUS Molecular Modelling Software, MSI/Biosym Inc., Cambridge, UK. 18 SMART (control) and SAINT (integration) software, Bruker Analytical X-ray Systems, Madison, WI, 1994; G. M. Sheldrick, SHELXTL, version 5.10, Bruker Analytical X-ray Systems, Madison, WI, 1997. Footnote † One of the bridging 4,4�-bipy ligands is disordered with one pyridyl ring adopting two different orientations for the ring containing N(3)C(23–27). The observed twists in the bridging 4,4�-bipy ligands between the mean planes of the pyridyl rings are 29.4° for rings containing N(1) and N(2); 23.4° for rings containing N(3)C(23–27) and N(4); 17.5° for rings containing N(3)C(23'–27') and N(4). They are approximately coplanar with the BiI2 moiety to which they are attached. CrystEngComm © The Royal Society of Chemistr