The Kinetics and Mechanism of Oxidation of Triethylenetetraaminehexaacetatocobaltate(II) Complex by Periodate Ion in AqueousMedium

Abstract

The kinetics and mechanism of oxidation of [Co(II)TTHA] 4− (where TTHA =Triehylenetetraaminehexaaceticacid) by periodate ion has been studied in aqueous acidic medium. The reaction has been investigated spectrophotometrically at λ max = 550 nm under pseudo-first-order condition by taking large excess of oxidant, [IO − 4 ] at pH = 4.0+0.02, I = 0.1 M (CH 3 COONa + NaNO 3 ) and at three different temperatures viz. 15 • C, 20 • C and 25 • C. The electron transfer reaction between [Co(II)TTHA] 4− and [IO − 4 ] obeys inner-sphere reaction pathway through the formation of long-lived intermediate complex which eventually get converted into a corresponding [Co(III)TTHA] 3− complex as final reaction product. The experimental observations have shown that the reaction exhibit first-order dependence in [Co(II)TTHA] 4− . The variation of pseudo-first-order rate constant (k obs ) with [IO − 4 ] keeping other reaction variables fixed at constant value is found to obey the following emperical equation.This rate law is consistent with a three step mechanistic scheme. The values of k obs are almost invariant with increasing pH and attributed due to the reaction of deprotonated form of [Co(II)TTHA] 4− complex and in the whole pH region. Eyring's equations has been used to calculate the activation parameters and found to be H # = 16.63 kJ mole −1 ; S # = -214.00 JK −1 mole −1 . These values are consistent with three step mechanistic scheme as proposed.

Kinetic Study of Ru(III) Promoted Oxidation of L-Tryptophan in an Anionic Surfactant Medium by Hexacyanoferrate(III)

“…The fundamental importance and immediate applications of redox/ligand exchange reactions of transition metal complexes in synthetic, analytical, and organometallic chemistry attracted many chemists for their kinetic study [13][14][15][16][17][18]. Numerous kinetic reports on oxidation of Fe(II)/Co(II) complexes and the metalcatalyzed Hg(II)/Ag(I), cyanide substitution from cyano complexes of Fe(II)/Ru(II) by heterocyclic ligand containing nitrogen has been reported by several authors [19][20][21].…”

Effect of cationic surfactant on Ru(III) catalyzed L‐glutamic acid oxidation by hexacyanoferrate(III)

“…Numerous chemists were drawn to the kinetic study of the ligand substitution/redox reactions of transition metal complexes due to their fundamental significance and practical applications in synthetic, analytical, and organometallic chemistry 9–12 . Several authors have published kinetic reports on the substitution of cyanide from [Fe/Ru (CN) 6 ] 3− catalyzed by metal [Ag(I)/Hg(II)] and the oxidation of Co(II)/Fe(II) complexes 13–15 .…”

“…Numerous chemists were drawn to the kinetic study of the ligand substitution/redox reactions of transition metal complexes due to their fundamental significance and practical applications in synthetic, analytical, and organometallic chemistry. [9][10][11][12] Several authors have published kinetic reports on the substitution of cyanide from [Fe/Ru (CN) 6 ] 3− catalyzed by metal [Ag(I)/Hg(II)] and the oxidation of Co(II)/Fe(II) complexes. [13][14][15] Additionally, the trace-level determination of used catalysts and medications/compounds that shows strong affinity towards catalyst has also been accomplished with success using these reactions.…”

Kinetic study of Hg(II)‐promoted substitution of cyanide from hexacyanoferrate(II) in an anionic surfactant medium by 2,2′‐bipyridine

“…The fundamental importance and numerous applications of oxidation–reduction (redox)/ligand exchange reactions involving transition metal complexes in synthetic, analytical, and organometallic chemistry have motivated many chemists to study their reaction kinetics (Iioka et al, 2019; Naik, Srivastava, Tiwari, et al, 2007; Naik, Srivastava, Verma, et al, 2007; Omondi et al, 2020). Numerous kinetic reports on oxidation of Fe(II)/Co(II) complexes and the metal‐catalyzed Hg(II)/Ag(I), cyanide substitution from cyano complexes of Fe(II)/Ru(II) by heterocyclic ligand containing nitrogen has been reported by several authors (Naik et al, 2005; Singh & Singh, 2013).…”