Electrochemical variational study of donor/acceptor orbital mixing and electronic coupling in cyanide-bridged mixed-valence complexes

The bridge-mediated charge-transfer kinetics of L(NH3)4Ru(super III)N-triple bond-CFe(super II)(CN 5)1- were studied. Differential-pulse voltammetry indicated positive shifts in E(sub f)(Ru) as NH3 is displaced progressively by 4-methylpyridine and the other electron-withdrawing ligands. Potential shifts of the indirectly disturbed redox site was also revealed. Differences in the estimates of orbital mixing for the species are accounted for by the geometric distance between donor and acceptor metal ions which can exceed the true charge-transfer distance.