Gas-phase metal sulfide cluster anions

Abstract

The formation of metal sulfide cluster anions by laser ablation of solids has been examined for most of the first-row transition metals. Maps of the compositions of the clusters [M_xS_y]^– show well defined continuous distributions of x vs. y for each metal, and the slope of each distribution is related to the position of the metal in the transition series. The 290 new molecular forms of metal sulfides range in size up to [Cu₄₅S₂₃]^–. Fourier-transform ion cyclotron resonance mass spectrometry revealed that the cluster anions have lifetimes of up to 100 s in vacuo. Experiments concentrating on the copper–sulfur anions showed their resistance to dissociation on energised collision with argon, and their general lack of reactivity, except with sulfur-containing reactants. In experiments designed to produce mixed-metal anions, cobalt has been shown to substitute for copper in many of the smaller anions. Geometrical structures and structural principles for the copper sulfide clusters are revealed by non-local density functional calculations.