The mononuclear oxidovanadium(V) complex [VO(L)(OEt)(EtOH)] (1), where H2L = Salicyloyl hydrazone of diacetyl monooxime, reacts separately with five different reactants viz. pyridine (py), 4-methylpyridine (4mepy), 4,4′bipyridine (4,4′bipy), 8-hydroxyquinoline (Hox) and KOH to yield the mononuclear oxidovanadium complexes [VO(L)(OEt)(py)] (2), and [VO(L)(OEt)(4mepy)] (3), the binuclear complex [VO(L)(OEt)]2(μ-4, 4′bipy) (4), the mononuclear bis chelate complex [VO(L)(ox)] (5) and the water soluble dioxidovanadium salt K[VO2L]·H2O (6) respectively. Complex 5 has been characterized by X-ray crystallography, and crystallizes in the orthorhombic space group Pna21 having a distorted octahedral O4N2 coordination environment. All five complexes are characterized by elemental analysis, various spectroscopic techniques (UV-Vis, IR, NMR and ESI Mass) and cyclic voltammetry. The spectral and electrochemical data of these five complexes are compared with those of the precursor complex. © 2013 Elsevier B.V. All rights reserved.

M SUTRADHAR

BARMAN T ROY

S GHOSH

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

Journal of Molecular Structure

The mononuclear oxidovanadium(V) complex VO(OEt)L (2), where L2- is the dianion of a diprotic tridentate ONO donor ligand, 2- hydroxyacetophenone-2-aminobenzoylhydrazone (H2L), has been synthesized by oxido-bridge splitting of the corresponding binuclear complex V2O3L2 (1) and structurally characterized by single crystal X-ray diffraction analysis, together with electrochemical and spectral studies. Splitting of the oxido-bridge was effected by refluxing 1 with excess triphenylphosphine in ethanol medium. The crystal structure of 2 is compared with that of the precursor binuclear complex 1. © 2012 Elsevier B.V. All rights reserved.

Synthesis of a mononuclear oxidovanadium(V) complex by bridge-splitting of the corresponding binuclear precursor

The reaction of VO(acac) 2 with the ONO-chelator obtained by the condensation of salicylaldehyde with 2-hydroxybenzoylhydrazine (H 2 L) in a monohydric alcohol (ROH) medium produces [VO(OR)L]-type oxidoalkoxido complexes (1-7) where R = Me, n Pr, i Pr, n Bu, i Bu, t Bu and n Pen. All the complexes show the metal atom to have a five-coordinate square pyramidal environment, although in some complexes there is an additional weak V⋯O interaction in the sixth axial position. In acetonitrile medium and in the presence of a cis-diol (ethylene glycol), H 2 L reacts with VO(acac) 2 to form a six-coordinate complex, [VO(OCH 2 CH 2 OH)L] (8). When the reaction is carried out in acetonitrile medium in the presence of 2-amino ethanol, a completely different type of product containing the square pyramidal complex anion [VO 2 L] - associated with the cation [NH 3 CH 2 CH 2 OH] + is obtained. It was noted previously that on being reacted with monodentate nitrogen donor bases B (which are stronger than pyridine), the [VO(OR)L] complexes react to form the same complex anion [VO 2 L] - associated with the corresponding cation [BH] + . The coordination environment around the V(V) acceptor center of the water soluble [BH] + [VO 2 L] - satisfies one of the several requirements for an efficient antidiabetic vanadium species such as water solubility, nature of donor atoms of the ligand and their disposition around the VO 2+ acceptor center. © 2011 Elsevier Ltd. All rights reserved.

Polyhedron

Oxidoalkoxidovanadium(V) complexes: Synthesis, characterization and comparison of X-ray crystal structures

Several bis-malonatooxidovanadium(IV) complexes of the general type [M 2(H2O)n][VO(mal)2(H2O)] (where M = Li(1), Na(2), K(3), Cs(4) and NH4(5); n = 3.5, 1, 3, 1 and 1, respectively) were isolated in good yield and high purity. These complexes were fully characterized by various physicochemical techniques (elemental analysis, UV-Vis, IR, EPR, CV, etc.) complexes 1, 2 and 3 were structurally characterized by single crystal X-ray diffraction technique. In vivo antidiabetic properties of bis-malonato complexes 1, 2, 3 and 5 have been studied using Streptozotocin induced diabetic rats. Significant lowering of blood sugar level has been noticed. At the same time these complexes were found to regulate secondary pathophysiological complications like liver damage and lowering of the total antioxidant status (TAS) in diabetic rats. Results of these study are expected to a expand the possibility of designing new oxidovanadium(IV) complexes of O,O chelating ligands with significant antidiabetic properties. © 2010 Elsevier B.V. All rights reserved.

Inorganica Chimica Acta

Malonato complexes of oxidovanadium(IV): Synthesis, structural characterization and exploration of their insulin mimetic properties

The present work reports the chemistry of a few oxidovanadium(IV) and (V) complexes of the ONS chelating ligand S-benzyl-β-N-(2- hydroxyphenylethylidine) dithiocarbazate (H2L). Major objective of this work is to arrive at some general conclusions about the influence of binding environment generated by the replacement of an O-donor center by a S-donor point in a ligand (of a similar arrangement of the other O- and N-donor points) on the redox behavior and on the structural features of comparable [VO(OEt)(ONS)] and [VO(OEt)(ONO)] complexes. Synthesis, characterization by various physicochemical techniques (UV-Vis, IR, EPR and elemental analysis), exploration of electrochemical activity of the oxidovanadium(V) complex [V VO(OEt)L] (1), the mixed ligand complex [VVO(N-O)L] (3) (where N-O is the mono anion of 8-hydroxyquinoline) and a binuclear complex [VVO(OEt)L]2(μ-4,4′-bipy) (2) are reported. Similar studies on of mixed ligand oxidovanadium(IV) complexes of the formula [VVO(N-N)L] (4,5) (where N-N = 2,2′-bipy and o-phen) are also presented here. The [VVO(OEt)L] complex is pentacoordinated and distorted square pyramidal, while the [VIV(N-N)L] complexes are hexacoordinated and octahedral. Structural features of the complex 1 were compared with the corresponding aspects of the previously reported analogous complex [VVO(OEt)(ONO)] (1′). © 2010 Elsevier B.V. All rights reserved.

Synthesis, structural characterization and electrochemical activity of oxidovanadium(IV/V) complexes of a diprotic ONS chelating ligand

Dinuclear trioxidic [{VOL}2μ-O] (1-4) complexes were synthesized from the reaction of [VIVO(acac)2] with an equimolar amount of H2L [H2L is the general abbreviation of hydrazone ligands (H2L1-4) derived from the condensation of benzoyl hydrazine with either 2-hydroxyacetophenone or its para substituted derivatives] in acetone or CH2Cl2 or acetonitrile. These V2O3L2 complexes were also obtained from the reaction of VOSO4 with H2L in the presence of two equivalents sodium acetate in aqueous-methanolic (50% V/V) medium and also from the decomposition of [VIVO(L)(bipy/phen)] complexes in CH2Cl2 solution. Black monoclinic crystals of 2 and 4 with C2/c space group were obtained from the reaction of [VIVO(acac)2], respectively, with H2L2 and H2L4 in acetone in which the respective ligands are bonded meridionally to vanadium in their fully deprotonated enol forms. The V-O bond lengths follow the order: V-O(oxo) &lt; V-O(oxo-bridged) &lt; V-O(phenolate) &lt; V-O(enolate). Complexes (1-4) are diamagnetic exhibiting LMCT transition band near 380 nm in CH2Cl2 solution and they are electroactive displaying a quasi-reversible reduction peak in the 0.14-0.30 V versus SCE region. The λmax and the reduction peak potential (Epc) values show linear relationships with the Hammett constant (σ) of the substituents in the hydrazone ligands. These dinuclear complexes are converted to the corresponding mononuclear cis dioxo complexes K(H2O)+[VVO2(L)]- (5-8) and mixed-ligand [VVO(L)(hq)] complexes on reaction, respectively, with two equivalents KOH in methanol and two equivalents 8-hydroxyquinoline (Hhq) in CHCl3. Ascorbic acid reduces the dioxovanadium(V) complexes reversibly under aerobic condition. © 2008 Elsevier Ltd. All rights reserved.

Synthesis, structure and solution chemistry of a family of dinuclear hydrazonato-vanadium(V) complexes with [OV(Î¼-O)VO]4+ core

Synthesis and characterization of mixed-ligand complexes using a precursor mononuclear oxidovanadium(V) complex derived from a tridentate salicylhydrazone oxime ligand

Journal	Data powered by TypesetJournal of Molecular Structure
Publisher	Data powered by TypesetELSEVIER SCIENCE BV
ISSN	0022-2860