Pressure-induced phase transition in mixed-valence gold complexes: Comparison of quasi-1D system with 3D system

Effects of hydrostatic pressure on Raman spectra have been investigated in mixed-valence (MV) gold complexes, i.e,, quasi-one-dimensional (quasi-1D) [ AuX(DBS)] [AuX3(DBS)] (X = Br and Cl, DDS = dibenzylsulfide) and three-dime nsional (3D) Cs2Au2X6 (X = Cl and Br) up to similar to 13 GPa at 300 K. We have observed the deactivation of a Raman-active An-X stretching mode under a critical pressure of P-C similar to8 GPa (similar to 17 GPa) for X = Br (X = Cl) in quasi-1D complexes, indicating a pressure-induced phase transit ion from the MV state to a single-valence (SV) state. The larger P-C value, as compared to the P-C similar to 7 GPa (similar to 11 GPa) fur the 3D com plex, is perhaps due to the larger relative displacement of the halogen ion s in the quasi-1D system.