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

摘要

The 1:1 tribenzylphosphane (PBn_3) complexes of gold(I)[(Bn _3P)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 [(Bn_3P)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) ? for the chloride and Au-Br 2.404(10), Au-P 2.229(4) A for the bromide. These contrast with the 1:1 adducts previously reported for copper(I), which take the form [Cu(PBn_3] _2][CuX_2]. The 1:2 AuX.:PBn_3 compounds that have been synthesised are formulated as [Au(PBn_3)_2] X·nH_2O (X = Cl, n = 1 or 2; X = I and BF_4, n = O). Single-crystal X-ray structures show that linearly two-coordinate centrosymmetric [Au(PBn_3)_2]~+ arrays are found in [Au(PBn_3)_2]Cl·H_2O and [Au(PBn _3)_2]BF_4 with Au-P bond lengths of 2.2988(7) and 2.3016(7) A for the chloride and 2.2975(7) A for the tetrafluoroborate. v(AuX) bands in the far-IR spectra of [(Bn_3P)AuX] are assigned at: 320 and 227 cm~(-1) for X = Cl and X = Br, respectively. The ~(31)P CP MAS NMR spectra of [(Bn_3P)AuX] (X = Cl, Br) and [Au(PBn _3)_2]X (X = Cl·H_2O, C1·2H _2O,1, BF_4) are reported, and the observation of _2J(PP) coupling in the spectrum of [Au(PBn_3) _2]Cl· 2H_2O is consistent: with the presence in this complex of noncentrosymmetric cations in which the two phosphorus atoms are inequivalent.