Photoreduction of IrCl62? complex in alcohol solutions and its reaction with hydroxyalkyl radicals

Abstract

The photochemistry of complex in simple alcohols have been studied using 2ϪIrCl 6 laser-flash photolysis. Single electron transfer from the solvent molecule to the light-excited complex has been shown to be the primary photochemical process. Quantum yields of the photoreduction of complex and the rate constants of its reaction with hydroxyalkyl 2ϪIrCl 6 radicals were determined at Deviations of the rate constants from Debye-Smo-200-330 K. luchowski equation for diffusion-controlled reactions are discussed.

Photochemistry of the IrCl6 2− complex in aqueous solutions in the presence of the bromide anions

“…It is interesting to study the phototransformations of the IrCl 6 2-complex for the determination of primary mechanisms in photochemistry of transition metal halide complexes. The IrCl 6 2-complex has an exclusively stable coordination sphere and is stable in aqueous solutions and in organic solvents.…”

“…Laser flash photolysis (308 nm) was applied to study photochemistry of the IrCl 6 2-complex in aqueous solutions in the presence of the Br -anions. The formation of the Br 2…”

“…The IrCl 6 2-complex has an exclusively stable coordination sphere and is stable in aqueous solutions and in organic solvents. The electronic absorption spectrum of IrCl 6 2- (Fig. 1) contains charge transfer bands in the UV-Vis spectral region and rather intense d-d bands in a ∼310 nm region, which partially overlap with the charge transfer bands.…”

“…[2][3][4][5][6][7][8] In alcoholic solutions the primary photoprocess involves the electron transfer from a solvent molecule to the excited complex, resulting in the reduction of the central ion and formation of hydroxyalkyl radicals. [3][4][5][6][7] The stepwise photosolvation of IrCl 6 2-occurs in acetonitrile solutions. 8 The study of photochemistry of aqueous solutions of IrCl 6 2-showed 9-12 that the nature of the products and the quantum yield of photolysis depend on the exciting light wavelength and the concentration of chloride ions in solu tion.…”

“…[3][4][5][6][7] The stepwise photosolvation of IrCl 6 2-occurs in acetonitrile solutions. 8 The study of photochemistry of aqueous solutions of IrCl 6 2-showed 9-12 that the nature of the products and the quantum yield of photolysis depend on the exciting light wavelength and the concentration of chloride ions in solu tion. 10, 11 The final photolysis products upon excitation in the region of the charge transfer band (254 nm) are the iridium(IV) complex IrCl 5 (H 2 O) -and the iridium(III) complex IrCl 5 (H 2 O) 2-.…”