KINETIC-STUDY OF OXYGEN-TRANSFER REACTIONS FROM OXO-MONOPEROXO COMPLEXES OF VANADIUM(V) TO THIOLATOCOBALT(III) COMPLEX IN WATER AND CONCENTRATED-SOLUTIONS OF ELECTROLYTES

[Co(en)(2)SCH2CH2NH2](2+) ion is oxidized to [Co(en)(2)SOCH2CH2NH2](2) by the oxo-monoperoxovanadium(V) complexes in aqueous media. These r eactions art accompanied by oxygen atom transfer from the peroxo ligan d to the coordinated sulfur atom. The relative reactivities for each s ubstrate stand in the order: [VO(O-2)(ada)](-) << [VO(O-2)nta](2-) app roximate to H2O2 approximate to [VO(O-2)(H2O)(4)](+) < [VO(O-2)(quin)( 2)](3-) << [VO(O-2)(H2O)(2)(pic)], where ada = N-(carbamoylmethyl)imin odiacetato(2-), nta = nitrilotriacetato(3-), quin = 2,3-pyridinedicarb oxylato(2-) and pic = 2-pyridinecarboxylato(1-) ligands. The effect of pH on the second order rate constant for oxidation by monoperoxo-nta complex is in the pH range 4.8-6.5 consistent with equation k(298.2 K) = 0.709 + 1.28. 10(5) [H+]. Two new oxo-monoperoxo complexes of vanad ium(V), NH4[VO(O-2)(ada)] . H2O and (NH4)(3)[VO(O-2)(quin)(2)] . 3 H2O were synthesized and characterized. The salt effects on the thiolatoc obalt(III) oxidation by vanadium(V) oxo-monoperoxo complexes as well a s by H2O2 were studied at 298.2 K in different, up to 5 M solutions of electrolytes. The results can be rationalized in terms of the salt-wa ter interactions.