A linear, trinuclear mixed valence complex [CoII{(μ-L)(μ-OAc)CoIII(NCS)}2] has been prepared and its molecular structure has been elucidated on the basis of X-ray crystallography [H2L = salen = 1,6-bis(2-hydroxyphenyl)-2,5-diazahexa-1,5-diene]. The complex contains a high-spin CoII and two terminal low-spin CoIII, i.e., it is a CoIII(S = 0){single bond}CoII(S = 3/2){single bond}CoIII(S = 0) trimer. © 2006 Elsevier B.V. All rights reserved.

ASHUTOSH GHOSH

Chemistry

S CHATTOPADHYAY

G BOCELLI

A MUSATTI

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

Inorganic Chemistry Communications

Three new mixed valence trinuclear Co(II/III) compounds [Co3L2(μ2-C6H5CO2 −)2(CH3CN)2](ClO4 −)2·(CH3CN)3 (1) [Co3LR 2(μ2-C6H5CO2 −)2(C6H5CO2 −)2]·(CH3CN)2 (2) and [Co3LR 2(μ2-C6H5CH[dbnd]CH–CO2 −)2(C6H5CH[dbnd]CH–CO2 −)2]·((CH3)2CO)2 (3) have been synthesized by reacting the di-Schiff base ligand [H2L] or its reduced analog [H2LR] (where H2L = N,N′-bis(salicylidene)-1,3-propanediamine) and (H2LR = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine) with cobalt perchlorate hexahydrate and sodium benzoate or sodium cinnamate. The complexes have been characterized by IR, UV–Vis and single crystal X-ray diffraction analyses. All the complexes are linear trinuclear species [CoIII–CoII–CoIII] in which two terminal octahedral CoIIIN2O2 cores coordinate to the central octahedral CoII ion through μ2-phenoxido oxygen atom and the bridging carboxylato ions. In addition, the complexes (2 and 3) derived from reduced Schiff base ligand have, rather unusually, a terminally coordinated carboxylato ion to CoIII, which is acetonitrile molecule in case of complex (1) with unreduced ligand. Complex 2 has been found to be an excellent functional model for the phenoxazinone synthase activity, in the aerial oxidation of 2-aminophenol to the corresponding 2-aminophenoxazine-3-one chromophore in acetonitrile solvent medium. Detailed kinetic data analysis of this oxidation reaction reveals a fairly high phenoxazinone synthase activity of 2 with kcat = 153.60 h−1. © 2017 Elsevier Ltd

Polyhedron

Mixed valence trinuclear cobalt (II/III) complexes: Synthesis, structural characterization and phenoxazinone synthase activity

A new homometallic trinuclear Ni(II) complex [(NiL)2Ni(NCS) 2] (1) and three heterometallic trinuclear Ni(II)-Zn(II)-Ni(II) complexes [(NiL)2Zn(NCS)2] (2), [(NiL)2Zn(NCS) 2(CH3OH)2]·2CH3OH (3) and {[(NiL)2Zn(NCS)2(CH3OH)2]} {[(NiL)2Zn(NCS)2]} (4) have been synthesized by using the "complex as ligand" approach with the "metalloligand" [NiL] (H2L = N,N′-bis(salicylidene)-1,3-propanediamine) and thiocyanate in different ratios. All the complexes have been structurally and magnetically characterized. In the isomorphous complexes 1 and 2, the two terminal square planar Ni atoms and the central octahedral nickel atom (in 1) or zinc atom (in 2) are arranged in a bent structure where two cis κN-SCN- thiocyanate ions are coordinated to the central atom. The chemical composition of 3 is very similar to that of 2 but, in 3, the central Zn atom is tetrahedral and the κN-SCN- thiocyanate ions occupy an axial position of each terminal nickel atom (which now are octahedral with the sixth position occupied by a methanol molecule). Complex 4 consists of two closely related trinuclear units 4A and 4B. In 4A, the coordination environments of the metals are identical to those of 3 whereas 4B is a "coordination position isomer" of complex 2 with the central square pyramidal Zn and one of the terminal square pyramidal Ni atoms coordinated by two κN-SCN- thiocyanate ions. Complex 4 is a unique example of a cocrystal formed by two similar trinuclear units (4A and 4B) where 4A is identical to an existing complex (3) and 4B is a "coordination position isomer" of another existing complex (2). © 2013 American Chemical Society.

Inorganic Chemistry

Isolation of two different Ni2Zn complexes with an unprecedented cocrystal formed by one of them and a "coordination positional isomer" of the other

A new Schiff base oriented Co(III) complex, (CoL)Cl4H2O (L = Schiff base), has been synthesized by careful design of the Schiff base ligand thorough oxidation of Co(II) to Co(III) during the reaction process. The complex has been characterized by single-crystal X-ray structure analysis and various spectral analyses. Structure analysis reveals that this monomeric complex crystallizes in triclinic P-1 space group. Supramolecular hydrogen bonding interactions among the guest water molecules and counter anion chloride leads to the formation of 1D water-chloride chain. A polymer anchored heterogeneous cobalt complex has been synthesized, characterized by various physicochemical techniques and successfully used for the oxidation of alkenes and sulfides using H2O2 as oxygen source. The influence of the various reaction parameters has been studied. The heterogeneous cobalt complex can be reused seven times without any significant loss in its catalytic activity. © 2013 Elsevier B.V. All rights reserved.

Journal of Molecular Catalysis A: Chemical

Synthesis, crystal structure and spectroscopic studies of a cobalt(III) Schiff base complex and its use as a heterogeneous catalyst for the oxidation reaction under mild condition

Mixed valence cobalt (II, III) systems, one binuclear Co IIICoII (1) and another novel cyclic trinuclear Co IIICoII2 (2) complexes based on hydroxyl rich Schiff base ligands are synthesized and structurally characterized by X-ray crystallography. Catalytic activity of 1 and 2 towards oxidation of 3, 5-di-tert-butylcatechol (3,5-DTBC) to its corresponding quinone (3,5-DTBQ) are investigated in MeOH and DMF. ESI-MS technique is employed to characterize the intermediates. © 2013 Elsevier B.V.

Syntheses, crystal structures and catecholase activity of new dinuclear and cyclic trinuclear mixed valence cobalt (II, III) complexes

Two new polynuclear complexes of Cu(II), [(CuL 1 )Cu(N 3 C 2 ) 2 ] n (1) and [(CuL 2 ) 2 Cu(N 3 C 2 ) 2 ] ·H 2 O (2), have been synthesized by reacting the "ligand complexes", [CuL 1 ] and [CuL 2 ] respectively with copper perchlorate and sodium dicyanamide (NaN 3 C 2 ) in ethanol-water, where the di-Schiff base ligands H 2 L 1 = N,N′-bis(salicylidene)-1,3-propanediamine and H 2 L 2 = N,N′-bis(α-methylsalicylidene)-1,3-propanediamine. Structural analysis shows that complex 1 is a 2D polymer formed by linking the dinuclear units through a μ 1,5 -dicyanamido bridge. It contains alternating helical chains of P and M types. Complex 2 is a discrete bent trinuclear species where phenoxido groups of two terminal "ligand complexes" coordinate to a central Cu(II) along with terminally coordinated dicyanamido anions. Both complexes exhibit irreversible reductive Cu(II)/Cu(I) and quasi-reversible oxidative Cu(II)/Cu(III) responses in cyclic voltammetry. The electrochemically generated Cu(I) species for both complexes are unstable and undergo disproportionation to Cu 0 and Cu 2+ . © 2012 Elsevier Ltd. All rights reserved.

Structural variations in polynuclear copper(II) complexes based on salicylaldimine type ligands along with dicyanamido co-ligand

First oxidative synthetic route of a novel, linear mixed valence Co(III){single bond}Co(II){single bond}Co(III) complex with bridging acetate and salen

Journal	Inorganic Chemistry Communications
Publisher	-
ISSN	1387-7003
Open Access	No