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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
Author(s) -
Sen Gupta Kalyan K.,
Bhattacharjee Nandini,
Pal Biswajit
Publication year - 2016
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.21022
Subject(s) - chemistry , picolinic acid , manganese , sodium dithionite , bond cleavage , pyridine , dithionite , stoichiometry , inorganic chemistry , tris , medicinal chemistry , reaction mechanism , kinetics , dipicolinic acid , catalysis , organic chemistry , biochemistry , physics , quantum mechanics , enzyme , botany , spore , biology
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:S 2 O 4 2 −+ 2MnIII + 2 H 2 O → 2 HSO 3 − + 2MnII + 2 H +The reaction is described in terms of a mechanism that involves an initial complex formation between S 2 O 4 2− and [Mn III (C 5 H 4 NCO 2 ) 3 ] followed by S–S bond cleavage to give 2HSO 3 − and [Mn II (C 5 H 4 NCO 2 ) 2 (H 2 O) 2 ] as the products via the formation of SO 2 ●− 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.