Fourier transform Raman spectroscopic study of pressure‐induced ligand bond activation in a molybdenum–sulfur cluster

Fourier transform Raman spectra of the prototype, triangular, transition metal–sulfur cluster anion [Mo 3 (S 2 ) 6 S] 2− were recorded at pressures up to 60 kbar with the aid of a diamond‐anvil cell (DAC). The pressure dependences (∂ν/∂ p ) of the Raman bands indicate a structural change at around 10–15 kbar. The SS stretching mode for the bridging disulfide ligands exhibits a slightly negative ∂ν/∂ p value (−0.08), suggesting that SS bonds are weakened, i.e. activated , at high pressures. This pressure‐induced activity parallels the observed nucleophilic substitution reactivity of the S 2 groups in this molybdenum cluster anion. In view of this, a preliminary investigation of the reaction between [Mo 3 (S 2 ) 6 S] 2− and CN − was undertaken in the solid state in the DAC under high pressure. Copyright © 2002 John Wiley & Sons, Ltd.