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A cis,fac-[RuCl2(DMSO)(3)(H2O)] complex exhibits ultrafast photochemical aquation/rearrangement
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.