Pressure and temperature effects on metal-to-metal charge transfer in cyano-bridged CoIII-FeII complexes

Abstract

The effects of pressure and temperature on the energy (Eop) of the metal-to-metal charge transfer (MMCT, FeII → Co III) transition of the cyano-bridged complexes trans-[L 14CoNCFe(CN)5]- and cis-[L 14CoNCFe(CN)5]- (where L14 = 6-methyl-1,4,8,11-tetraazacyclotctradecan-6-amine) were examined. The changes in the redox potentials of the cobalt and iron metal centres with pressure and temperature were also examined and the results interpreted with Marcus-Hush theory. The observed redox reaction volumes can mainly be accounted for in terms of localised electrostriction effects. The shifts in Eop due to both pressure and temperature were found to be less than the shifts in the energy difference (Δ..