title: Gaussian free-energy dependence of electron-transfer rates in iridium complexes.
abstract: The kinetics of photoinduced electron-transfer (ET) reactions have been measured in a series of synthetic donor-acceptor complexes. The electron donors are singlet or triplet excited iridium(I) dimers (Ir(2)), and the acceptors are N-alkylpyridinium groups covalently bound to phosphinite ligands on the Ir(2) core. Rate constants for excited-state ET range from 3.5 x 10(6) to 1.1 x 10(11) per second, and thermal back ET (pyridinium radical to Ir(2)(+)) rates vary from 2.0 x 10(10) to 6.7 x 10(7) per second. The variation of these rates with driving force is in remarkably good agreement with the Marcus theory prediction of a Gaussian free-energy dependence.
authors.forename: L S
authors.initials: LS
authors.lastname: Fox
authors.forename: M
authors.initials: M
authors.lastname: Kozik
authors.forename: J R
authors.initials: JR
authors.lastname: Winkler
authors.forename: H B
authors.initials: HB
authors.lastname: Gray