Machanism of cobalt dithiolene complex catalysis of thiol autoxidation in acidic acetonitrile solution

Abstract

Sunz+naryThe efficient catalysis by [C~(mnt),],~-(mnt = maleonitriledithiolate) of the reaction 2PhCH,SH + 0, + PhCH,SSCH,Ph + H,O, in acetonitrile, acid-buffered with excess of PhMe,N/PhMe,NH+ClO,-, is described ; the mechanism involves sequential co-ordinative activation of thiol and oxygen, the reactive intermediate being PhMe,NH--0,-[Co (mnt),],-SCH,Ph2-.

Catalysis of thiol oxidation by cobalamins and cobinamides: reaction products and kinetics

“…The fact that earlier studies involving corrinoid-catalyzed thiol oxidation (Aronovitch & Grossowicz, 1962;Peel, 1963) failed to identify hydrogen peroxide as the other initial product of these reactions may have been due to secondary reactions involving the oxidation of thiols by hydrogen peroxide (Slater, 1952). Hydrogen peroxide has been identified as the primary product of aerobic thiol oxidation catalyzed by copper ion (Slater, 1952;De Marco et al, 1971), other metal ions (Capozzi and Modena, 1974), and cobalt-dithiolene complex (Dance et al, 1974). The rate of 02 disappearance during corrinoid-catalyzed thiol oxidation was dependent upon both catalyst and thiol concentration.…”

Oxygen activation by transition metal complexes. 2. Bis(acetylacetonato)cobalt(II)-catalyzed oxidation of tributylphosphine

“…Soc., 96, 7117 (1974). (12) It is possible that even [Fe°] is the "active catalyst" since Fe(CO)5 is almost as effective as Fe(acac)a in catalyzing pinacol formation. (13) I.…”

“…Thus these oxygen complexes catalyze the oxi-dation8"10 or oxidative coupling10•11 of phenols and thiols. 12 Metal-superoxide complexes are also intermediates in the Journal of the American Chemical Society / 98:21 / October formation of a third major class of oxygen adducts, the binuclear µ-peroxides.13 These diamagnetic complexes are generally less reactive than their superoxide precursors, but it is possible to envision a means of oxygen activation which might be open to certain binuclear µ-peroxides, i.e., the formation of reactive oxometal species via homolytic dissociation of the central 0-0 bond. In this paper we describe the Co(acac)2catalyzed oxidation of tributylphosphine and present evidence for the catalytic activation of molecular oxygen by such a "reductive-dissociation" process.…”