Co-ordination and conformational isomerism in bis(tricyclohexylphosphine) gold(I) halides

Abstract

Solid state complexes of bis(tricyclohexylphosphine)gold(I) with halide counter ions, Au(PCy₃)₂X (X = Cl, Br or I), have been crystallised from solutions of [NBu₄][AuX₂] and PCy₃ in dimethylformamide and characterised by single crystal structure determinations, far-infrared spectroscopy and solid state ³¹P CP MAS NMR spectroscopy. The results show the complexes crystallise as a unique array of co-ordination and conformational isomers which reflect the conformational flexibility of the tricyclohexylphosphine ligand and the relative preferences of the halide anions for C–H  · · ·  X^–versus Au⁺  · · ·  X^– bonding interactions. The chloride crystallises as a single ionic complex, [Au(PCy₃)₂]⁺Cl^–, with the gold two-co-ordinate and the cations and anions well separated in the crystal lattice. The bromide crystallises as three different polymorphs with four distinct molecular structures. The first (α) form crystallises as ionic [Au(PCy₃)₂]⁺Br^– with the bromide adjacent to but not co-ordinated to the gold. The second (β) form presents two crystallographically independent [Au(PCy₃)₂Br] molecules with semi-co-ordinated bromide and significant differences in the conformational dispositions of the PCy₃ ligands. The third (γ) form crystallises as [Au(PCy₃)₂Br] with fully co-ordinated bromide. The iodide crystallises with semi-co-ordinated and co-ordinated iodide in [Au(PCy₃)₂I]·PCy₃ and [Au(PCy₃)₂I] complexes respectively. The study provides an unusual series of molecular ‘vignettes’ in which the response of the [Au(PCy₃)₂]⁺ cation to halide anion can be monitored as it passes through the ligand substituents and co-ordinates to the central gold atom.

References

1. E. Zeller, A. Schier and H. Schmidbaur, Z. Naturforsch., Teil B, 1994, 49, 1243.
2. J. A. Muir, M. M. Muir, L. B. Pulgar, P. G. Jones and G. M. Sheldrick, Acta Crystallogr., Sect. C, 1985, 41, 1174.
3. K. Angermaier, E. Zeller and H. Schmidbaur, J. Organomet. Chem., 1994, 472, 371.
4. Z. Assefa, R. J. Staples and J. P. Fackler, Acta Crystallogr., Sect. C, 1996, 52, 305.
5. N. C. Baenziger, K. M. Dittmore and J. R. Doyle, Inorg. Chem., 1974, 13, 805.
6. G. A. Bowmaker, J. C. Dyason, P. C. Healy, L. M. Engelhardt, C. Pakawatchai and A. H. White, J. Chem. Soc., Dalton Trans., 1987, 1089.
7. G. C. H. Jones, P. G. Jones, A. G. Maddock, M. J. Mays, P. A. Vergnano and A. F. Williams, J. Chem. Soc., Dalton Trans., 1977, 1440.
8. E. N. de Silva, G. A. Bowmaker and P. C. Healy, unpublished data.
9. R. W. Buckley, P. C. Healy and W. A. Loughlin, Aust. J. Chem., 1997, 50, 775.
10. S. R. Hall, H. D. Flack and J. M. Stewart, The Xtal 3.2 Reference Manual, Universities of Western Australia, Geneva and Maryland, 1992.
11. G. M. Sheldrick, SHELXL 97, Program for Structure Refinement, University of Göttingen, 1997.
12. TEXSAN, Crystal Structure Analysis Package, Molecular Structure Corporation, Houston, TX, 1992.
13. M. K. Cooper, G. R. Dennis, K. Hendrick and M. McPartlin, Inorg. Chim. Acta, 1980, 45, L151.
14. J. A. Muir, M. M. Muir and E. Lorca, Acta Crystallogr., Sect. B, 1980, 36, 931.
15. W. A. Anderson, A. J. Carty, G. J. Palenik and G. Schreiber, Can. J. Chem., 1971, 49, 761.
16. R. J. Restivo, A. Costin and G. Ferguson, Can. J. Chem., 1975, 53, 1949.
17. J. A. Davies, S. Dutremez and A. A. Pinkerton, Inorg. Chem., 1991, 30, 2380.
18. G. L. Soloveichik, O. Eisenstein, J. T. Poulton, W. E. Streib, J. C. Huffman and K. G. Caulton, Inorg. Chem., 1992, 31, 3306.
19. G. A. Bowmaker, Effendy, P. J. Harvey, P. C. Healy, B. W. Skelton and A. H. White, J. Chem. Soc., Dalton Trans., 1996, 2449.
20. M. Barrow, H. B. Burgi, M. Camalli, F. Caruso, E. Fischer, L. M. Venanzi and L. Zambonelli, Inorg. Chem., 1983, 22, 2356.
21. H. B. Buergi, R. W. Kunz and P. S. Pregosin, Inorg. Chem., 1980, 19, 3707.
22. F. Caruso, M. Camalli, H. Rimmi and L. M. Venanzi, Inorg. Chem., 1995, 34, 673.
23. P. G. Jones, A. G. Maddock, M. J. Mays, M. M. Muir and A. F. Williams, J. Chem. Soc., Dalton Trans., 1977, 1434.
24. R. C. Bott, G. A. Bowmaker, R. W. Buckley, P. C. Healy and M. C. S. Perera, Aust. J. Chem., 1999, in the press.
25. A. Bayler, A. Schier, G. A. Bowmaker and H. Schmidbaur, J. Am. Chem. Soc., 1996, 118, 7006.
26. J. Emsley, The Elements, Oxford University Press, Oxford, 1989.
27. C. B. Colburn, W. E. Hill, C. A. McAuliffe and R. V. Parish, J. Chem. Soc., Chem. Commun., 1979, 218.
28. S. J. Berners-Price and P. J. Sadler, Inorg. Chem., 1986, 25, 3822.
29. J. D. Dunitz and J. Bernstein, Acc. Chem. Res., 1995, 28, 193.
30. D. Dakternieks, Inorg. Chim. Acta, 1984, 89, 209.
31. T. Allman and R. E. Lenkinski, Inorg. Chem., 1986, 25, 3202.
32. L. J. Baker, R. C. Bott, G. A. Bowmaker, P. C. Healy, B. W. Skelton, P. Schwerdtfeger and A. H. White, J. Chem. Soc., Dalton Trans., 1995, 1341.
33. K. P. Huber and G. Herzberg, Constants of Diatomic Molecules, Van Nostrand, New York, 1979.
34. P. G. Jones, Z. Naturforsch., Teil B, 1982, 37, 823.
35. J. Browning, P. L. Goggin, R. J. Goodfellow, M. G. Norton, A. J. M. Rattray, B. F. Taylor and J. Mink, J. Chem. Soc., Dalton Trans., 1977, 2061.
36. N. C. Baenziger, W. E. Bennett and D. M. Soboroff, Acta Crystallogr., Sect. B, 1976, 32, 962.
37. P. G. Jones, G. M. Sheldrick, J. A. Muir, M. M. Muir and L. B. Pulgar, J. Chem. Soc., Dalton Trans., 1982, 2123.
38. G. A. Bowmaker, Adv. Spectrosc., 1987, 14, 1.
39. G. A. Bowmaker and D. A. Rogers, J. Chem. Soc., Dalton Trans., 1984, 1249.
40. G. A. Bowmaker, P. C. Healy, J. D. Kildea and A. H. White, Spectrochim. Acta, 1988, 44, 1219.
41. G. A. Bowmaker, Effendy, J. D. Kildea and A. H. White, Aust. J. Chem., 1997, 50, 577.