Resonance Raman spectra of the complex pentacyano‐4‐cyanopyridineferrate(II) and its 4‐cyanopyridine‐bridged binuclear complex with a ruthenium(II) pentaamine unit

Abstract

AbstractComparative resonance Raman effect (RRE) studies of both the 4‐cyanopyridine complex with the pentacyanoferrate(II) anion, the first [Fe(CN)5L]3− anion studied by RRE, and a binuclear complex formed by this anion with 4‐cyanopyridine as bridging ligand and a pentaamineruthenium(II) moiety are reported. The RR spectra obtained show differences in the number of enhanced modes in each case. The spectroscopic data suggest coordination of the Fe(CN)5 unit through the pyridine nitrogen of 4‐cyanopyridine in both the mononuclear and the binuclear complex. Assignment of the electronic spectra as being due to metal to ligand charge transfer (MLCT) (FeII → pyridine‐N, 4‐cyanopyridine) is proposed for the bands at 476 nm (aqueous solution) and 470 nm (solid dispersion in KBr) in both the mononuclear and the binuclear complex, respectively, and MLCT (RuII → nitrile, 4‐cyanopyridine) for the band at 418 nm (solid) observed in the binuclear complex only.Excitation profiles of the 1600 cm−1 bands in the mononuclear complex (in acetonitrile‐methanol solution) and of the 1607, 1207 and 1020 cm−1 bands in the binuclear complex (as solid) were obtained and are interpreted.