Cationic phosphine complexes of gold(I): an electrospray mass spectrometric study

Abstract

Electrospray (ES) mass spectra have been observed for a number of cationic gold(I) phosphine derivatives in dichloromethane/methanol solution. For complexes of the types [Au(PR 3) 2] + and [Au(PR 3) 3] + the intact ions were observedbut ions of the type [Au(PR 3) 4] + were not detected in the gas phase. The tris(ligand) complexes [Au(PR 3) 3] + are relatively unstable in the gas phase and the product ions [Au(PR 3) 2] + are readily produced by collisional activation, either in the electrospray ion source or by using tandem mass spectrometry. In solution, mixed ligand gold(I) complexes are known to exchange rapidly on the NMR timescale at room temperature, but ESMS techniques can identify the individual components of such mixtures. Reactions in solution between ClAu(PPh 3) and a number of potentially bidentate diphosphine and related ligands have been monitored by ESMS. The ES technique provides a unique insight into the changing equilibria which occur in solution as the relative proportions of the constitutents change.