title: Catalysis of the Electroreduction of O(2) to H(2)O by Vanadium-salen Complexes in Acidified Dichloromethane.
abstract: Addition of stoichiometric quantities of trifluoromethanesulfonic (triflic) acid to solutions of V(IV)O(salen) (H(2)salen = N,N '-ethylenebis(salicylideneamine)) in dichloromethane produces the &mgr;-oxo dinuclear vanadium(IV) complex [(salen)V(IV)OV(IV)(salen)](2+) ([V(IV)OV(IV)](2+)). Addition of significant excesses of triflic acid converts the dimer into [V(IV)(salen)](2+). In dichloromethane solutions containing 0.1 M tetrabutylammonium tetrafluoroborate, the [V(IV)OV(IV)](2+) complex undergoes disproportionation and dissociation reactions to produce a solution containing an equimolar mixture of V(IV)O(salen), [V(III)(salen)](+), and [V(IV)OV(V)](3+). The oxophilic [V(III)(salen)](+) complex reacts with O(2) to accomplish a four-electron reduction of O(2): 2[V(III)(salen)](+) + O(2) --> 2[V(V)O(salen)](+). These reactions can be exploited to carry out catalytic electroreductions of O(2) to H(2)O in acidified dichloromethane solutions of V(IV)O(salen) at unusually positive potentials.
authors.affiliation: Advanced Research Institute for Science and Engineering, Department of Polymer Chemistry, Waseda University, Tokyo 169-8555, Japan, and Arthur Amos Noyes Laboratories, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125.
authors.forename: Eishun
authors.initials: E
authors.lastname: Tsuchida
authors.forename: Kenichi
authors.initials: K
authors.lastname: Oyaizu
authors.forename: Eniya Listiani
authors.initials: EL
authors.lastname: Dewi
authors.forename: Takahiro
authors.initials: T
authors.lastname: Imai
authors.forename: Fred C.
authors.initials: FC
authors.lastname: Anson