摘要
The vibrational and electronic structures of diruthenium nickel and copper complexes [Ru 2 Ni(dpa) 4 Cl 2 ] 0,1+ and [Ru 2 Cu(dpa) 4 Cl 2 ] 0,1+ were studied by using temperature-controlled Raman spectroscopy and density functional theory (DFT) calculations. In the neutral species, the Ru−Ru stretching mode ν Ru−Ru was assigned to the 333/325 cm −1 band for the diruthenium Ni/Cu complexes, and this band greatly red shifted to 317/321 cm −1 at high temperatures. In contrast, this ν Ru−Ru band showed no shift in the oxidized forms. The time-dependent DFT (TD-DFT) calculations yielded that these complexes in the neutral form, have [Ru 2 ] 5+ [M] 1+ cores with [Ru 2 ] moiety configuration (π*) 2 (δ*) 1 and two low-lying electronic excited states with [Ru 2 ] 4+ [M] 2+ cores and [Ru 2 ] configurations of (π*) 2 (δ*) 2 and (π*) 3 (δ*) 1 , respectively. The significant red shift of ν Ru−Ru band was explained to thermally access to these two excited states which have [Ru 2 ] 4+ cores and weak Ru−Ru bonding. These two states were resulted from metal-to-metal intramolecular charge transfer processes from [Ru 2 ] 5+ [Ni/Cu] 1+ to [Ru 2 ] 4+ [Ni/Cu] 2+ . This charge transfer reaction is prohibited in the oxidized form.