Identification of various electrochemical processes in the ruthenium complexes with a redox-active ligand by in situ spectroscopy and time-dependent density functional theory calculations

Spectroelectrochemistry was used to investigate the spectra during reduction and oxidation of cis-[Ru(NH3)4(tetrachrolocatecholate)]PF6 and during reduction of cis-[Ru(NH3)4(3,5-di-tert-buthylbenzoquinone)](PF6)2. Time-dependent density functional theory calculations were performed to identify the oxidation states of the reduced and oxidized species of the complexes. Comparing the observed spectrum with the calculated one, the proposed oxidation states of each complex are as follows. The oxidation states of the isolated and one-electron reduced species of the tetrachrolodioxolene complex were found to be trivalent ruthenium–catecholate and divalent ruthenium–catecholate, respectively. The oxidation states of the isolated and two-electron reduced species of the 3,5-di-tert-buthyldioxolene complex were found to be divalent ruthenium–benzoquinone and divalent ruthenium–catecholate, respectively.