Vibrational and electronic spectra of Ru2(O2CH)4+

Vibrational (near-infrared and Raman) spectra of Ru2(O2CH)4Cl and K[Ru2(O2CH)4Cl2] indicate values of ν(Ru2) ≅ 330 cm-1, symmetric and asymmetric ν (RuCl) of 200 and 150 cm -1, and ν(RuO) of ∼ 430 (a1g) and ∼ cm-1 (eu). Near-infrared low-temperature electronic spectra place the δ → δ* and π* → δ* electronic transitions at ∼ 9000 and ∼ 7000 cm-1, respectively. For both chloro complexes, and also for [Ru2(O2CH)4Br2]- (formed in KBr), three vibrations coupled to δ → δ* have similar Franck-Condon factors; excited-state values are ν(Ru2) ∼ 275-310 cm-1, ν(RuO) ∼ 420-440 cm-1, and ν ∼ 140-210 cm-1 attributable to δ(Ru2O) or ν(Ru-halide). The vibronic intensities observed for the formate complexes are compared to those of other carboxylate derivatives, and its is concluded that strong vibrational coupling of ν(Ru2) with other vibrational modes is present in the formates