Synthesis and crystal structure of an unusual bimetallic mercuryndash;dithiolene complex

摘要

S S S S O 2 S S S S Hg S S S Hg S S S S S 1 i, ii, iii NBun 42 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(14) C(15) C(16) C(17) C(18) C(19) C(20) C(21) C(22) C(23) C(24) C(25) C(26) C(27) C(28) C(29) C(30) C(31) C(32) C(33) C(34) C(35) C(36) C(37) C(38) C(39) C(40) C(41) C(42) C(43) C(44) C(45) C(46) C(47) C(48) S(1) S(2) S(3) S(4) S(5) S(6) S(7) S(8) S(9) S(10) S(11) S(12) Hg(1) Hg(2) Synthesis and crystal structure of an unusual bimetallic mercuryndash;dithiolene complex Dong-Youn Noh,a Allan E.Underhill*b and Michael B. Hursthousec a Department of Chemistry, Seoul Womens University, Seoul 139-774, Korea b Department of Chemistry, University of Wales, Bangor, Gwynedd, UK LL57 2UW c Department of Chemistry, University of Wales, Cardiff, PO Box 912, UK CF1 3TB A bimetallic mercury(II) dithiolene complex in which the ligand exhibits three different modes of coordination to the mercury atoms within the same molecular species is reported.Metal dithiolene complexes have been widely studied because of their potential in applications such as molecular conductors, ferromagnets, IR dyes, liquid crystals and catalysis.1ndash;3 As part of an extensive programme of research into these unusual compounds we have been studying the synthesis and properties of metal complexes of ligands derived from dmit (dmit = 1,3- dithiol-2-thione-4,5-dithiolate). During the course of these studies we have prepared a bimetallic mercury(ii)ndash;dithiolene complex 1, which has a most unusual structure involving three differing modes of coordination by the same dithiolene ligand and contains a three-coordinate HgII.Here we report the synthesis and X-ray crystal structure of 1. The synthesis of the mercuryndash;dithiolene complex 1 is outlined in Scheme 1. The 1,3-dithiole-2-one 2 was treated with KOH dissolved in MeOH under N2 to open the five-membered ring.5 To the solution were added separate solutions of HgCl2 and TBABr in MeOH.The yellow precipitate was filtered off and washed with MeOH. The precipitate was recrystallised from acetonendash;ethyl acetate in a freezer to yield 1dagger; in 32 yield. Surprisingly, the precursor (or an intermediate thereof) has undergone oxidative dehydrogenation during this reaction to yield the fully conjugated system 1,4-dithiacyclohexadiene observed in 1. The crystal structure of 1Dagger; and selected interatomic parameters are presented in Fig. 1 and show two mercury atoms bridged and chelated by three dithiolene ligands, each of which have different binding modes.One ligand simply chelates a mercury ion, Hg(2), whilst another ligand acts as a normal m2 bridge between Hg(1) and Hg(2) and the final ligand chelates Hg(1) and further bridges via one sulfur to Hg(2). As far as we are aware these variations in ligand behaviour (and indeed the resulting formations of oligomers) are unique in the area of dithiolate chemistry, but similar features are known in b-diketonate clusters.6 The two mercury centres are in different coordination environments.Hg(1) is three coordinate with a very distorted trigonal planar geometry which is due to the ligand bonding constraints. Hg(2) however is four coordinate with very distorted tetrahedral geometry. These multiple forms of coordination have introduced considerable strain into the complex, as may be seen upon investigation of the Hgndash;S bond lengths. the conventionally coordinated ligand produces expected bond lengths Hg(2)ndash;S(5), Hg(2)ndash;S(6).However around Hg(1) a longer bond is observed for the bridging sulfur S(2) and a shortening is seen for the chelating sulfur atoms S(3), S(9). A lengthening is also observed for the Hg(2)ndash;S(2) bridging sulfur, whilst the Hg(2)ndash;S(10) bond has the expected length. We thank the EPSRC and KOSEF for financial support. Scheme 1 Reagents and conditions: i, KOH, MeOH, room temp.; ii, HgCl2, MeOH then NBun 4Br, MeOH; iii, recrystallization from acetonendash;ethyl acetate, 32 yield Fig. 1 The single-crystal X-ray structure of NBun 4Hg2(dithiolene)3, with ellipsoids shown at 50 probability and NBun 4+ ions omitted. For clarity only mercury and sulfur atoms are labelled, with all other atoms being carbon. Selected bond lengths (Aring;) and angles (deg;): Hg(1)ndash;S(1) 2.367(3), Hg(1)ndash;S(2) 2.609(2), Hg(1)ndash;S(9) 2.348(3), Hg(2)ndash;S(2) 2.748(2), Hg(2)ndash; S(5) 2.502(2), Hg(2)ndash;S(6) 2.484(2), Hg(2)ndash;S(10) 2.481(3); S(1)ndash;Hg(1)ndash; S(2) 88.31(8), S(1)ndash;Hg(1)ndash;S(9) 155.40(8), S(2)ndash;Hg(1)ndash;S(9) 115.24(7), S(2)ndash;Hg(2)ndash;S(5) 108.31(8), S(2)ndash;Hg(2)ndash;S(6) 114.44(8), S(2)ndash;Hg(2)ndash; S(10) 95.26(9), S(5)ndash;Hg(2)ndash;S(6) 88.52(7), S(5)ndash;Hg(2)ndash;S(10) 120.97(8), S(6)ndash;Hg(2)ndash;S(10) 129.47(10).Chem. Commun., 1997 2211Footnotes and References * E-mail: CH5013@bangor.ac.uk dagger; Selected analysis data for 1, yellow crystal (from acetonendash;ethyl acetate), mp 180ndash;181 deg;C. Elemental analysis: calc. C, 51.11; H, 5.47; N, 1.49; S, 20.42 for C80H102Hg2N2S12; observed.C 51.04, H 5.89, N 1.11, S 21.34. FTIR (KBr, cm21): 1479.9, 1451.4, 1378.0 (CNC), 765.8, 718.8, 694.6, (Cndash;H phenyl) 513.5, 435.4, 408.8. Dagger; Crystal data: C80H102Hg2N2S12, Mr = 1877.54, triclinic, space group P1 (no. 2), a = 12.144(2), b = 12.219(2), c = 29.588(8) Aring;, a = 96.82(4), b = 91.326(9), g = 99.380(5)deg;, U = 4297.3(14) Aring;, Z = 2, Dc = 1.451 g cm23, F(000) = 1896, m(Mo-Ka) = 3.90 cm21. Data were collected at 293(2) K, for a crystal of dimensions 0.24 3 0.24 3 0.215 mm, on a FAST TV Area detector diffractometer following previously described procedures. 12291 data were recorded and merged to give 8421 unique (Rint = 0.0669). The structure was solved via heavy-atom methods (SHELX),8 to give two independent molecules in the asymmetric unit and then refined by full-matrix least squares on all F0 2 data (SHELX-93).9 An absorption correction was applied using DEFABS.10 The final R, Rw indices I 2s(I) were 0.0368, 0.0710 for 873 parameters (non-hydrogen atoms anisotropic hydrogen atoms in idealised positions, Cndash;H = 0.96 Aring;, with Uiso tied to Ueq of the parent atoms).CCDC 182/620. 1 P. Cassoux, L. Valade, H. Kobayashi, R. A. Clark and A. E. Underhill, Coord. Chem. Rev., 1991, 110, 115. 2 C. S. Winter, S. N. Oliver, J. D. Rush, C. A. S. Hill and A. E. Underhill, J. Mater. Chem., 1992, 2, 443; T. Bjoslash;rnholm, T. Geisler, J. C. Petersen, D. R. Greve and N. C. Schioslash;dt, Non-linear Optics, 1995, 10, 129. 3 A. T. Coomber, D. Beljonne, R. H. Friend, J. L. Br�edas, A. Charlton, N. Robertson, A. E. Underhill, M. Kurmoo and P. Day, Nature, 1996, 380, 144. 4 A. E. Underhill, N. Robertson, J. Ziegenbalg, N. Le Narvor, J. D. Kilburn and K. Awaga, Mol. Cryst. Liq. Cryst., 1996, 284, 39. 5 D.-Y. Noh, H.-J. Lee, J. Hung and A. E. Underhill, Tetrahedron Lett., 1996, 37, 7603. 6 V-Cumaran Arunasalam, S. R. Drake, M. B. Hursthouse, K. M. A. Malik, S. A. S. Miller and D. M. P. Mingos, J. Chem. Soc., Dalton Trans., 1996, 12, 2435. 7 S. R. Drake, M. B. Hursthouse, K. M. A. Malik and S. A. S. Miller, Inorg. Chem., 1993, 32, 4653. 8 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467. 9 G. M. Sheldrick, University of G�ottingen, 1993, unpublished work. 10 N. P. C. Walker and D. Stuart, Acta Crystallogr., Sect. A, 1983, 39, 158; adapted for FAST geometry by A. Karaulov, University of Wales, Cardiff, 1991. Received in Cambridge, UK, 4th September 1997; 7/06460H 2212 Chem. Commun.,