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 = k_on [Cr(CH₃CN)₆²⁺][NS] (k_on = 2.3 x 10⁸ M^-1 s^-1 at 298 K).  Photolysis of 1 in deaerated acetonitrile with the added Fe(S₂CNEt₂)₂ leads to transfer of NS and formation of a species concluded to be Fe(S₂CNEt₂)₂(NS) based on its EPR 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)₆²⁺ (3).  When 1 was photolyzed in aerated acetonitrile solution, the reactive species 3 is 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 formation of S₈, presumably from the decomposition of NS. The quantitative photochemical behaviors of 1 and the nitrosyl analog 2 are compared.
Udgivelsesdato: Jan.