Sequential photooxidation of a Pt(II) (diimine)cysteamine complex: intermolecular oxygen atom transfer versus sulfinate formation.
The thiolato complex [platinum(II) (bipyridine)(N,S-aminoethanethiolate)](+)Ch(-) (1) undergoes sequential reactions with singlet oxygen to initially form the corresponding sulfenato complex [platinum(II) (bipyridine)(N,S(═O)-aminoethansulfenate)](+) (2) followed by a much slower reaction to the corresponding sulfinato complex. In contrast with many platinum dithiolato complexes, 1 does not produce any singlet oxygen, but its rate constant for singlet oxygen removal (k(T)) is quite large (3.2 × 10(7) M(-1) s(-1)) and chemical reaction accounts for ca. 25% of the value of k(T). The behavior of 1 is strikingly different from that of the complex platinum(II) (bipyridine)(1,2-benzenditholate) (4). The latter complex reacts with (1)O(2) (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 (1)O(2) must involve O-O bond cleavage and intermolecular oxygen atom transfer, while the reactive intermediate in complex 4 collapses intramolecularly to the sulfinato moiety.
Department of Chemistry and Biochemistry, California State University, Los Angeles, Los Angeles, California 90032, United States.
Dong
D
Zhang
Ye
Y
Bin
Lorillee
L
Tallorin
Florence
F
Tse
Blanca
B
Hernandez
Errol V
EV
Mathias
Timothy
T
Stewart
Robert
R
Bau
Matthias
M
Selke
D018360:Crystallography, X-Ray; D003543:Cysteamine / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009944:Organoplatinum Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D055668:Photochemical Processes; D010984:Platinum / Q000737:chemistry*; D013441:Sulfinic Acids / Q000138:chemical synthesis* / Q000737:chemistry
D007097:Imines; D009944:Organoplatinum Compounds; D013441:Sulfinic Acids; D010984:Platinum; D003543:Cysteamine; D010100:Oxygen