Structural and spectroscopic characterisation of linearly coordinated gold(I) tribenzylphosphane complexes

Ainscough, Eric W. and Bowmaker, Graham A. and Brodie, Andrew M. and Freeman, Graham H. and Hanna, John V. and Healy, Peter C. and Robinson, Ward T. and Skelton, Brian W. and Smith, Mark E. and Sobolev, Alexandre N. and White, Allan H. (2010) Structural and spectroscopic characterisation of linearly coordinated gold(I) tribenzylphosphane complexes. European Journal of Inorganic Chemistry, 2010 (13). pp. 2044-2053. ISSN 1099-0682

Abstract

The 1:1 tribenzylphosphane (PBn3) complexes of gold(I)-?(Bn3P)AuX? (X = Cl and Br) have been synthesised, and their structures were determined by single-crystal X-ray crystallography. The compounds are isomorphous, neutral molecules with linearly coordinated P-Au-X arrays. Each structure contains three independent ?(Bn3P)AuX? entities lying on the three threefold axes of space group P3c1. The mean bond lengths are Au-Cl 2.302(8), Au-P 2.227(11) angstrom for the chloride and Au-Br 2.404(10), Au-P 2.229(4) angstrom for the bromide. These contrast with the 1:1 adducts previously reported for copper(I), which take the form ?Cu(PBn3)(2)??CuX2?. The 1:2 AuX:PBn3 compounds that have been synthesised are formulated as ?Au(PBn3)(2)?X center dot nH(2)O (X = Cl, n = 1 or 2; X = I and BF4, n = 0). Single-crystal X-ray structures show that linearly two-coordinate centrosymmetric ?Au(PBn3)(2)?(?) arrays are found in ?Au(PBn3)(2)?Cl center dot H2O and (Au(PBn3)(2)?BF4 with Au-P bond lengths of 2.2988(7) and 2.3016(7) angstrom for the chloride and 2.2975(7) angstrom for the tetrafluoroborate. v(AuX) bands in the far-IR spectra of ?(Bn3P)AuX? are assigned at 320 and 227 cm(-1) for X = Cl and X = Br, respectively. The P-31 CP MAS NMR spectra of ?(Bn3P)AuX? (X = Cl, Br) and ?Au(PBn3)(2)?X (X = Cl center dot H2O, Cl center dot 2H(2)O, I, BF4) are reported, and the observation of (2)J(PP) coupling in the spectrum of ?Au(PBn3)(2)?Cl center dot 2H(2)O is consistent with the presence in this complex of noncentrosymmetric cations in which the two phosphorus atoms are inequivalent.