No abstract

The thiolato complex [Pt(II)(bipyridine)(N,S-aminoethanethiolate)]+ Cl- (1) undergoes sequential reactions with singlet oxygen to initially form the corresponding sulfenato complex [Pt(II)(bipyridine)(N,S(=O)-aminoethansulfenate)]+ (2) followed by a much slower reaction to the corresponding sulfinato complex. In contrast with many Pt dithiolato complexes, 1 does not produce any singlet oxygen, but its rate constant for singlet oxygen removal (kT) is quite large (3.2 × 107 M-1sec-1) and chemical reaction accounts for ca. 25 % of the value of kT). The behavior of 1 is strikingly different from the complex Pt(II)(bipyridine)(1,2-benzenditholate) (4). The latter complex reacts with 1O2 (either from an external sensitizer or via a self-sensitized pathway) to form a sulfinato complex. These two very different reactivity pathways imply different mechanistic pathways: The reaction of 1 with 1O2 must involve O-O bond cleavage and intermolecular oxygen atom transfer, while the reactive intermediate in complex 4 collapses intramolecularly to the sulfinato moiety.