The metal ion (M2+) catalysed dissociation of cis‐diaquobisoxalatochromate into the tetraaquomonooxalato complex in aqueous perchloric acid medium which follows the rate law — d(complex)/dt = {kH[H+] + kM[M2+]}[complex] has been studied. Based on kM values the order of catalysing effect of the different metal ions studied is Cu2+ &gt; Ni2+ &gt; Co2+ &gt; Mn2+, which is also the order of stabilities (KMOx) of the monooxalato complexes of these metal ions; in fact the plot of log kM vs. log KMOx is linear. This together with the relative values of ΔH≠ and ΔS≠ for the H+ catalysed and M2+ catalysed paths is in agreement with a mechanism involving chelation of the catalysing cation through the free carbonyl oxygens of the oxalate ligand bound to Cr(III), followed by the dissociation of the Cr(III)O bonds with simultaneous entry of two water molecules into the coordination sphere of Cr(III). Copyright © 1977 Verlag GmbH &amp; Co. KGaA, Weinheim

L GOSWAMI

S SARKAR

D BANERJEA

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

ZAAC â€ Journal of Inorganic and General Chemistry

Transition Metal Chemistry

Mechanisms of reactions of metal complexes: Some recent developments

Dissociation of oxalato complexes of chromium (III) of the type [Cr(ox)n(OH2)6-2n](3-2n)+ into [Cr(ox)n-1 (OH2)4-2n](5-2n)+(where n = 1, 3) promoted by different metal ions of the first transition series in acid perchlorate media has been investigated spectrophotometrically. In comparable cases the order of the catalytic activity as measured by the second-order rate constant kM, follows the sequence Fe3+ >> Cu2+> Ni2+ > Zn2+ > Co2+> Mn2+. Log kM for a particular substrate complex and different promoter metal ions of same charge varies linearly with log km-ox, kM-ox being the formation constant of the mono-oxalato complex of the catalysing metal ion Mn+. The value of kH+ for the acid catalysed reaction occupies a position intermediate between kCo2+ and kMn2+, and even for the positively charged complex [Cr(ox)(OH2)4]+, Fe3+ is a far better catalyst than H+, indicating the importance of specific bonding between the promoter and the substrate complex in the intermediate step. These conclusions are corroborated by various free energy relationships and also by comparing results of the present work with literature data on other similar systems. Reactions of a particular substrate complex as promoted by different metal ions and also that by H+ are all practically iso-enthalpic. © 1984, Taylor & Francis Group, LLC. All rights reserved.

Journal of Coordination Chemistry

Mechanism of metal ion promoted dissociation of some oxalato complexes of chromium(iii)

The Cu(II), Ni(II), Co(II) and Zn(II) catalysed dissociation of the cis-diaquobis(malonato)chromate(III) ion has been studied kinetically in perchloric acid solution over a temperature range. Under these conditions kobs = kH[H+] + Kcat [M2+] where kobs is the observed first order rate constants and kH and Kcat are the appropriate rate constants for the proton and metal ion catalysed pathways respectively. The metal ion exert marked catalytic effects with kcat following the sequence Cu(II) &gt; Ni(II) &gt; Co(II) &gt; Zn(II). A possible mechanism for the metal promoted reaction is proposed and the relevance of these results to the mechanism of the trans → cis isomerisation of [Cr(mal)2 (H2O)2]- considered. © 1981 Gordon and Breach Science Publishers, Inc.

Kinetics and mechanism of the metal ion catalysed aquation of cis-diaquobis(malonato) chromate (III) ion in aqueous-acid media

The sodium salt of the [N-(o-carboxyphenyl)iminodiacetato]picolinatochromate(III) complex has been synthesised and characterised. In acidic media, the complex has been shown to aquate to diaqua[N-(o-carboxyphenyl)imminodiacetato]chromium(III) and picolinic acid as the ultimate products. The enhanced kinetic stability exhibited by the aromatic amino acid (cida) may be attributed to (i) resonance interaction of the carboxyl and tertiary nitrogen group with the phenyl ring resulting in a shortening of the bond distance and thus leading to a closer approach of the chelate donor groups, (ii) the presence of a larger number (two five-membered and one six-membered ring) of chelate rings in the ligated amino acid, in comparison to only one five-membered metal - picolinato ring. The variation of the observed pseudo-first-order rate constants with perchloric acid concentration suggests the operation of two concurrent uncatalysed and acid-catalysed pathways. The reaction exhibits a solvent deuterium isotope effect kD/kH = 1.5 at 45 °C. The solvent deuterium isotope effect is consistent with a rapid pre-equilibrium protonation followed by rate-determining ring opening and excludes a mechanism involving concerted attack by [H3O+]. The metal ions, Cu2+, Ni2+, and Zn2+, promoted hydrolysis in weakly acidic medium has been studied as a function of metal ion concentration and temperature. The metal ion catalysed aquation is proposed to take place through a rapid pre-equilibrium step to form a binuclear complex with the M2+ ion, followed by the cleavage of the Cr-O bond in a slow rate-determining step. The catalytic efficiency of the metal ion follows the Irving - Williams order of stability and also parallels the log kM-pic values. © 2001 Elsevier Science Ltd. All rights reserved.

Polyhedron

Acid and metal ion promoted hydrolysis of [N-(o-carboxyphenyl)iminodiacetato](picolinato)chromate(III) complex: A mechanistic study

European Journal of Inorganic Chemistry

Further Masthead: Eur. J. Inorg. Chem. 5-6/2013

Journal of Engineering Science and Technology Review

Identification of Mass -­ Unbalance in Rotor of an Induction Motor Through Envelope Analysis of Motor Starting Current at no Load

JurPC

10.7328/jurpcb/200722690

Critical Stability Constants

Protonation Values for Other Ligands

Entwicklung der Berlin-Frage

81. Mitteilung des Presseamtes beim Vorsitzenden des Ministerrates der DDR über das Verbot des Transportes von Gegenständen für militärische Zwecke der BRD vom 28. Februar 1969

Mechanism of Metal Ion Catalysis in the dissociation of cisâ€diaquobisoxalatochromate(III) ion

Journal	ZAAC â€ Journal of Inorganic and General Chemistry
Publisher	-
ISSN	0044-2313