A comparative study on metal-metal interaction in binuclear two- and three-coordinated d~(10)-metal complexes Spectroscopic investigation of M(I)-M(I) interaction in the ~1[dσ~*pσ] excited state of [M_2(dcpm)_2]~(2+) (dcpm = bis(dicyclohexylphosphino)

摘要

An overview of an UV-vis spectroscopic and resonance Raman investigation of the lowest energy dipole-allowed absorption band of [M_2(dcpm)_2]~(2+) (M = Au, Ag, Cu) and [M_2(dmpm)_3]~(2+) (M = Au, Ag, Cu) complexes is presented. The UV-vis absorption spectra of [M_2(dcpm)_2]~(2+) and [M_2(dmpm)_3]~(2+) feature intense low energy ndσ~* → (n+1)pσ transition with transition energy increase from two- to three-coordinated complexes and for [M_2(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 [Au_2(dcpm)_2]~(2+) and [Au_2(dmpm)_3]~(2+) complexes but significantly different for the [Cu_2(dcpm)_2]~(2+) and [Cu_2(dmpm)_3]~(2+) complexes that have weaker metal-metal bonding.