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It is known that both cis,fac-[RuCl2(DMSO)3(H2O)] (1a) and trans,cis,cis-[RuCl2(DMSO)2(H2O)2] (2a) complexes, which are formed on the dissolution of trans and cis-isomers of [RuCl2(DMSO)4] in water, demonstrate light-induced anticancer activity. The first stage of 1a photochemistry is its transformation to 2a occurring with a rather high quantum yield, 0.64 ± 0.17. The mechanism of the 1a→2a phototransformation was studied by means of nanosecond laser flash photolysis and ultrafast pump–probe spectroscopy. The reaction occurs in the picosecond time range via the formation and decay of two successive intermediates interpreted as Ru(ii) complexes with different sets of ligands. A tentative mechanism of phototransformation is proposed. [ABSTRACT FROM AUTHOR]

Two mechanisms of OsIVCl62− photolysis were studied by means of quantum chemical calculations in gas and aqueous phases. The difference between these mechanisms is in the nature of the possible Os(iv) key intermediates (KI). According to calculations, the intermediate is an OsIVCl5− complex of square pyramidal coordination geometry. The calculations do not give an opportunity to make an unambiguous choice between the triplet and quintet multiplicities of OsIVCl5−. The calculated CASSCF/IMCP-SR1 transition energies for 5OsIVCl5− are lower than for 3OsIVCl5−, while the calculated XMC-QDPT2/SBKJC spectra for the triplet state are in better agreement with the experimental absorption spectrum of the KI than for the quintet state. [ABSTRACT FROM AUTHOR]

The photoaquation of the OsIVCl62− complex was studied by means of stationary photolysis, nanosecond laser flash photolysis and ultrafast kinetic spectroscopy. The OsIVCl5(OH)2− complex was found to be the only reaction product. The quantum yield of photoaquation is rather low and wavelength-dependent. No impact of redox processes on photoaquation was revealed. The total characteristic lifetime of the process is about 80 ps. Three intermediates were recorded in the femto- and picosecond time domains and assigned to different Os(iv) species. The nature of intermediates and possible mechanisms of photoaquation are discussed. [ABSTRACT FROM AUTHOR]

Photochemistry of the ( n -Bu 4 N) 2 [PtCl 6 ] complex in chloroform was studied by means of stationary photolysis and nanosecond laser flash photolysis. The results were explained in the framework of the chain photosolvation. The chain character of photolysis was supported by the quantum yield dependencies on the concentration of the initial complex and light intensity. Spectra of two successive Pt(III) intermediates were registered, their spectral and kinetic characteristics were determined. Based on the obtained experimental data, the literature mechanism of photolysis was revised. [ABSTRACT FROM AUTHOR]

The quantum yield of As III oxidation caused by the UV photolysis (282 nm) of fulvic acid H108498 in aqueous solution was measured and a qualitative model explaining its dependence upon pH and As III concentration was suggested. [ABSTRACT FROM AUTHOR]