Oxidative Cleavage of S–S Bond During the Reduction of Tris(pyridine‐2‐carboxylato)manganese(III) by Dithionite in Sodium Picolinate–Picolinic Acid Buffer Medium

Abstract

The reduction of tris(pyridine‐2‐carboxylato)manganese(III) by dithionite has been investigated within the temperature window 288–303 K and at pH range 5.22–6.10 in sodium picolinate–picolinic acid buffer medium. The reaction obeys the following stoichiometry: truerightnormalS2normalO42−+2 Mn III +2H2normalO→2 HSO 3−+2 Mn II +2normalH+ The reaction is described in terms of a mechanism that involves an initial complex formation between S2O42− and [MnIII(C5H4NCO2)3] followed by S–S bond cleavage to give 2HSO3− and [MnII(C5H4NCO2)2(H2O)2] as the products via the formation of SO2●− radical anion. Kinetics and spectrophotometric evidences are cited in favor of the suggested mechanism. Thermodynamic parameters associated with the equilibrium step and the activation parameters with the rate‐determining step have been computed.

A Low-cost Manganese Complex Catalyst for Phenolic Coupling and Further Oxidation of Phenols

“…Complex (1) can be easily synthesized in one step which does not required expensive starting materials. Complex (1) has been used in many studies, such as redox chemistry [22][23][24][25][26] and in oxidation reactions [27][28][29] .…”

Application of Piszkiewicz model on the electron transfer reaction of dithionite ion and bis-(2-pyridinealdoximato)dioxomolybdate(IV) complex

“…Ukoha et al 4 noted nonexistence of catalysis with added cation and anion, an increment in redox rate with a rise in [H + ], and an invariant in reaction rate of reduction of adipato bridge iron(III)-salen complex with S 2 O 4 2− as ion concentration and system medium permittivity varied. Gupta et al 5 recorded free radical generation and intermediate complex formation, and S-S bond cleavage to give 2HSO 3 − ion for the reduction of tris-(pyridine-2-carboxylato)manganese(III) by dithionite in sodium picolinate-picolinic acid buffer medium.The chemistry of complexation of molybdenum from higher to lower oxidation states is of great interest due to its role as enzymes in nitrogen metabolism and as a vital micronutrient in lower animals. It can be found in soybeans, chicken liver, cow milk, rabbit liver, hog liver, bovine liver, azotobacter, and coli in different forms of enzymes 6 .…”

“…Ukoha et al 4 noted nonexistence of catalysis with added cation and anion, an increment in redox rate with a rise in [H + ], and an invariant in reaction rate of reduction of adipato bridge iron(III)-salen complex with S 2 O 4 2− as ion concentration and system medium permittivity varied. Gupta et al 5 recorded free radical generation and intermediate complex formation, and S-S bond cleavage to give 2HSO 3 − ion for the reduction of tris-(pyridine-2-carboxylato)manganese(III) by dithionite in sodium picolinate-picolinic acid buffer medium.…”