title: Flash and continuous photolysis studies of the thionitrosyl complex Cr(CH3CN)5(NS)2+ and the nitric oxide analogs: reactions of nitrogen monosulfide in solution.
abstract: Photolysis of the thionitrosyl complex Cr(CH3CN)5(NS)2+ (1) in acetonitrile solution leads to the dissociation of nitrogen monosulfide (NS). In deaerated solution, this reaction is reversible, and flash photolysis studies demonstrate that NS reacts with Cr(CH3CN)62+ according to the rate law d[1]/dt = kon[Cr(CH3CN)62+][NS] (kon = 2.3 x 108 M-1 s-1 at 298 K). The photolysis of 1 in deaerated acetonitrile with added Fe(S2CNEt2)2 leads to the transfer of NS and the formation of a species concluded to be Fe(S2CNEt2)2(NS) based on its electron paramagnetic resonance spectrum. Analogous photolysis of 1 in the presence of added NO leads to clean formation of the nitrosyl complex Cr(CH3CN)5(NO)2+ (2) presumably by NO capture of the photoproduct Cr(CH3CN)6(2+) (3). When 1 was photolyzed in aerated acetonitrile solution, the reactive species 3 was trapped, thus leading to net photochemical transformations with excitation-wavelength-dependent quantum yields of 0.3-1.0 mol/Einstein. Mass spectroscopic studies of the product solutions demonstrate the formation of S8, presumably from the decomposition of NS. The quantitative photochemical behaviors of 1 and the nitrosyl analog 2 are compared.
authors.affiliation: Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.
authors.forename: Johannes W
authors.initials: JW
authors.lastname: Dethlefsen
authors.forename: Erik D
authors.initials: ED
authors.lastname: Hedegård
authors.forename: R Dale
authors.initials: RD
authors.lastname: Rimmer
authors.forename: Peter C
authors.initials: PC
authors.lastname: Ford
authors.forename: Anders
authors.initials: A
authors.lastname: Døssing