Affiliations: Department of Chemistry, University of Patras, Patras, Greece
Note: [] Corresponding author: P.V. Ioannou, Department of Chemistry, University of Patras, GR 26504, Patras, Greece. Fax: +30 2610 997118; E-mail: ioannou@chemistry.upatras.gr
Abstract: Bismuth nitrate pentahydrate, Bi(NO3)3·5H2O, reacts with aliphatic and aromatic thiols giving trithiolates, Bi(SR)3 and Bi(SAr)3, some of them being catalytically active for the air oxidation of their thiols to disulfides. The process most likely involves activation of triplet dioxygen by Bi(III) to give Bi(V) esters [(RS)3BiO]x and [(ArS)3BiO]x. These esters decompose intramolecularly to their disulfides and Bi(III) subthiolates (RS-BiO)x/(ArS-BiO)x which in the presence of excess thiols regenerate the trithiolates, repeating the cycle. Nitric acid, released from bismuth nitrate, may also be involved as an oxidant. Bis(dimethylarsinato)(nitrato)bismuth(III) monohydrate, (Me2AsO2)2Bi(NO3)·H2O, catalyzes the autoxidation of certain thiols to their disulfides. It acts by either forming Bi(III) trithiolates, as in the case of Bi(NO3)3·5H2O or, when the cacodylate groups are not stripped off the Bi(III), by probably generating peroxynitric acid. The synthetic usefulness of these reagents are assessed and probable biochemical implications of these findings are discussed.
