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

Abstract

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.