title: Redox reactivity of photogenerated osmium(II) complexes.
abstract: Powerful reductants [Os(II)(NH(3))(5)L](2+) (L = OH(2), CH(3)CN) can be generated upon ultraviolet excitation of relatively inert [Os(II)(NH(3))(5)(N(2))](2+) in aqueous and acetonitrile solutions. Reactions of photogenerated Os(II) complexes with methyl viologen to form methyl viologen radical cation and [Os(III)(NH(3))(5)L](3+) were monitored by transient absorption spectroscopy. Rate constants range from 4.9 × 10(4) M(-1) s(-1) in acetonitrile solution to 3.2 × 10(7) (pH 3) and 2.5 × 10(8) M(-1) s(-1) (pH 12) in aqueous media. Photogeneration of five-coordinate Os(II) complexes opens the way for mechanistic investigations of activation/reduction of CO(2) and other relatively inert molecules.
authors: Beckman Institute, California Institute of Technology, 1200 E. California Blvd., MC 139-74, Pasadena, California 91125, USA.
authors: Jillian L
authors: JL
authors: Dempsey
authors: Jay R
authors: JR
authors: Winkler
authors: Harry B
authors: HB
authors: Gray