title: Molecule-bridged mixed-valent intermediates involving the Ru I oxidation state.
abstract: The diruthenium(II) complexes {(mu-L)[RuCl(Cym)]2}(PF6)n, Cym = p-cymene = 4-isopropyltoluene, L = 2,2'-azobispyridine = abpy and n = 1, or L = 2,5-bis(1-phenyliminoethyl)pyrazine = bpip and n = 2, were synthesized and characterized by NMR (n = 2) or EPR spectroscopy (n = 1). Whereas the (n = 1) species are ligand radical-bridged RuIIRuII complexes, the three-electron reduction under loss of both chloride ions produces the ions {(mu-L)[Ru(Cym)]2}+, which could be identified as RuI(4d7)-containing mixed-valent species (Ru0RuI or RuIRuII) through UV-vis-NIR spectroelectrochemistry (intervalence charge-transfer bands around 1500 nm) and EPR (rhombic g tensor anisotropy). The weak metal-metal interaction of the dsigma electrons from the eg set is responsible for the small electrochemical coupling with comproportionation constants Kc approximately 102.
authors.affiliation: Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany.
authors.forename: Biprajit
authors.initials: B
authors.lastname: Sarkar
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kaim
authors.forename: Jan
authors.initials: J
authors.lastname: Fiedler
authors.forename: Carole
authors.initials: C
authors.lastname: Duboc