A comparative study on metal-metal interaction in binuclear two- and three-coordinated d10-metal complexes

An overview of an UV-vis spectroscopic and resonance Raman investigation of the lowest energy dipole-allowed absorption band of [M2(dcpm)2]2+ (M = Au, Ag, Cu) and [M2(dmpm)3]2+ (M = Au, Ag, Cu) complexes is presented. The UV-vis absorption spectra of [M2(dcpm)2]2+ and [M2(dmpm)3]2+ feature intense low energy ndσ* → (n + 1)pσ transition with transition energy increase from two- to three-coordinated complexes and for [M2(dcpm)2]2+ falls in the order: Ag > Au > Cu. A resonance Raman intensity analysis of the spectra allows estimation of the structural changes of the 1[dσ*pσ] excited states relative to the ground state. The structural changes in these compounds are compared with each other and with other related compounds. The metal-metal bonds are found to be very similar for the ground and excited states of the [Au2(dcpm)2]2+ and [Au2(dmpm)3]2+ complexes but significantly different for the [Cu2(dcpm)2]2+ and [Cu2(dmpm)3]2+ complexes that have weaker metal-metal bonding.