Gas-phase synthesis and reactivity of binuclear gold hydride cations, (R3PAu)2H+ (R = Me and Ph)

Abstract

Electrospray ionization of a mixture of the two gold phosphine chlorides, R₃PAuCl (R = Ph and Me), silver nitrate and the amino acid N,N-dimethylglycine (DMG) yields a range of gold containing cluster ions including: (R₃P)Au(PR′₃)⁺; (R₃PAu)(R′₃PAu)Cl⁺ and (R₃PAu)(R′₃PAu)(DMG-H)⁺ (where R = R′ = Ph; R = R′ = Me; R = Me and R′ = Ph). Collision induced dissociation (CID) of the (R₃PAu)(R′₃PAu)(DMG-H)⁺ precursor ions yielded the hitherto unknown gold hydride dimers (R₃PAu)(R′₃PAu)H⁺. The gas-phase chemistry of these dimers was studied using ion–molecule reactions, collision induced dissociation, electronic excitation dissociation (EED) and DFT calculations on the (H₃PAu)₂H⁺ model system. A novel phosphine ligand migration was found to occur prior to fragmentation under CID conditions and this was supported by DFT calculations, which revealed a transition state with a bridging phosphine ligand.