Electron-transfer rates by dielectric relaxometry and the direct-current conductivities of solid homonuclear and heteronuclear mixed-valence metal cyanometallates and of the Methylene Blue–iron dithiolate adduct

Dielectric relaxation (DR) frequencies for electron transfer in a series of metal hexacyanometallates have been compared with values from d.c. conductivity. If the compounds do not show evidence of proton conduction, the agreement is good, so establishing a site-transfer electronic conduction mechanism. Cu2Fe(CN)6 shows some disagreement, while marked anomalies with CoII3[CoIII(CN)6] and FeII3[CrIII(CN)6]2 are ascribed to proton conduction and electrode processes. Despite variation from sample to sample in the Methylene Blue–dithiolate adduct, the relaxation/conductivity relationships for each is also satisfactory for this single-metal-ion complex, bis[3,7-bis(dimethylaminophenazathionium)] tris(maleonitriledithiolato) iron2–.