Four new nickel(ii) complexes, [Ni2L2(NO 2)2]·CH2Cl2·C 2H5OH, 2H2O (1), [Ni2L 2(DMF)2(μ-NO2)]ClO4·DMF (2a), [Ni2L2(DMF)2(μ-NO2)] ClO4 (2b) and [Ni3L'2(μ3-NO 2)2(CH2Cl2)]n·1. 5H2O (3) where HL = 2-[(3-amino-propylimino)-methyl]-phenol, H 2L' = 2-({3-[(2-hydroxy-benzylidene)-amino]-propylimino}- methyl)-phenol and DMF = N,N-dimethylformamide, have been synthesized starting with the precursor complex [NiL2]·2H2O, nickel(ii) perchlorate and sodium nitrite and characterized structurally and magnetically. The structural analyses reveal that in all the complexes, NiII ions possess a distorted octahedral geometry. Complex 1 is a dinuclear di-μ2-phenoxo bridged species in which nitrite ion acts as chelating co-ligand. Complexes 2a and 2b also consist of dinuclear entities, but in these two compounds a cis-(μ-nitrito-1κO:2κN) bridge is present in addition to the di-μ2-phenoxo bridge. The molecular structures of 2a and 2b are equivalent; they differ only in that 2a contains an additional solvated DMF molecule. Complex 3 is formed by ligand rearrangement and is a one-dimensional polymer in which double phenoxo as well as μ-nitrito-1κO:2κN bridged trinuclear units are linked through a very rare μ3-nitrito-1κO:2κN:3κO′ bridge. Analysis of variable-temperature magnetic susceptibility data indicates that there is a global weak antiferromagnetic interaction between the nickel(ii) ions in four complexes, with exchange parameters J of -5.26, -11.45, -10.66 and -5.99 cm-1 for 1, 2a, 2b and 3, respectively. © The Royal Society of Chemistry 2011.

ASHUTOSH GHOSH

Chemistry

S NAIYA

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

Dalton Transactions

A diphenoxido bridged dinuclear Ni(II) complex [Ni2L2(NO2)2] (1) and a μ2and μ3-phenoxido, μ3-hydroxido, and μ2-nitrito (1κO:2κN) bridged trinuclear Ni(II) complex [Ni3L3(OH)(NO2)]·ClO4(2), have been synthesized using a tridentate reduced Schiff base ligand HL (HL = 2-[(2-dimethylamino-ethylamino)-methyl]-phenol). Both complexes were characterized by X-ray structure determination and variable-temperature magnetic susceptibility measurements. In both complexes the nickel atoms are six-coordinated with a distorted octahedral environment. The interesting feature of the trimeric complex 2 is that the three mononuclear units are assembled around a μ3-hydroxido ion in such a way that the three phenoxido groups and one nitrito group form a cyclic bridge that markedly modify the magnetic properties. Complex 1 presents a moderate antiferromagnetic Ni–Ni coupling (J = −39 cm−1) through the phenoxido bridges with a wide Ni–O–Ni bond angle of 101.77(6)° whereas the lower Ni–O–Ni bond angles, in the range 86.66(6)–96.07(7)°, lead to a moderate ferromagnetic coupling (J = +18.2 cm−1) in the trimeric complex 2 with a weak antiferromagnetic contribution (J′ = −0.51 cm−1) via the 1κO:2κN nitrito bridge. © 2016 Elsevier Ltd

Polyhedron

Formation of a dinuclear and a trinuclear Ni(II) complex on slight variation of experimental conditions: Structural analysis and magnetic properties

Two dinuclear [Ni2L2(o-(NO2)C 6H4COO)2(H2O)] (1), [Ni 2L2(p-(NO2)C6H4COO) 2(H2O)]·0.5CH3OH (2) complexes and one trinuclear [Ni3L2(p-(NO2)C6H 4COO)4]·C2H5OH (3) Ni(ii) complex have been synthesized using a tridentate Schiff base ligand, 1-[(3-dimethylamino-propylimino)-methyl]-naphthalen-2-ol (HL) along with ortho- and para-nitro benzoate as co-ligands. All these three (1-3) complexes have been characterized by spectral analysis, X-ray crystallography and variable temperature magnetic susceptibility measurements. The structural analyses reveal that complexes 1 and 2 are dinuclear in which two μ2-phenoxido and a water molecule bridge the two Ni(ii) centers to make the complexes face sharing bioctahedra. Complex 3 is a linear triple bridged (phenoxido and carboxylato) trinuclear Ni(ii) complex. Variable-temperature magnetic susceptibility studies indicate the presence of ferromagnetic exchange coupling in complexes 1-3 with J values of 25.4, 28.1 and 6.2 cm-1 respectively. Theoretically obtained J values of 21.4 cm-1 (for 1), 22.0 cm-1 (for 2) and 9.3 cm-1 (for 3) corroborate very well the experimental results. DFT calculation also shows that stronger H-bonding interactions present in the case of carboxylate based coligands stabilise the triple oxido-bridged complexes. This journal is © the Partner Organisations 2014.

Triple-bridged ferromagnetic nickel(ii) complexes: A combined experimental and theoretical DFT study on stabilization and magnetic coupling

Two new Fe(III) complexes of formulas [FeL1(N 3)(OMe)]2 (1) and [FeL2(N3)(OH)] 2·H2O (2) have been synthesized by using two tridentate NNO-donor Schiff base ligands HL1{(2-[(3- methylaminoethylimino)-methyl]-phenol)} and HL2 {(2-[1-(2- dimethylaminoethylimino)methyl]-phenol)}, respectively. Substitution of the -CH3 group on the secondary amine group of the N,N-dimethyldiamine fragment of the Schiff base by a H-atom leads to a structural change from a methoxido-bridged dimer (1) to a single hydroxido-bridged dimer (2). Both complexes have been characterized by single-crystal X-ray analyses, IR and UV-Vis spectroscopy and DFT studies. Both dimers are centrosymmetric containing two FeIII atoms which are bridged by two methoxido ions in compound 1 and by two hydroxido ions in compound 2. The chelating tridentate Schiff base and a terminal azido group complete the distorted octahedral environment around each iron center in both complexes. To explain the preferential bridging ability of methoxido and hydroxido groups in complexes 1 and 2, we have carried out theoretical calculations based on DFT to compare their formation energies and dimerization energies. In the case of complex 2, it is noticed that the close proximity of the azido group from the iron centers allow the hydroxido bridged complex to gain extra stability through H-bonds, whereas due to the steric crowding of the azido group and the methyl moiety of adjacent molecules, complex 1 disfavors the formation of hydrogen bonds as well as hydroxido bridging. © 2014 Elsevier Ltd. All rights reserved.

Fulltext

Structural and theoretical investigation on two dinuclear Fe(III) complexes of tridentate NNO-donor Schiff base ligands

Three new Ni(II) complexes, [NiL(NO2)(H2O)] (1), [Ni2L2(PhCH2COO)2(H2O)] (2) and [Ni2L2(N(CN)2)2(H 2O)] (3), have been synthesized using a tridentate Schiff base ligand, 1-[(3-dimethylamino-propylimino)-methyl]-naphthalen-2-ol (HL) and the polyatomic monoanions NO2-, PhCH2COO - or N(CN)2-. All three complexes (1-3) have been characterized by spectral analysis and X-ray crystallography. Structural analyses reveal that complex 1 is mononuclear, in which the Ni(II) ion is in a distorted octahedral environment, coordinated by the deprotonated tridentate Schiff base (L), a chelating nitrite and one water molecule. The structures of both 2 and 3 consist of dinuclear octahedral Ni(II) units with crystallographic C2 symmetry. In complex 2, two μ2-phenoxido and a water molecule bridge the two Ni(II) centers to make the complex a face sharing bioctahedron, whereas in 3 the Ni(II) atoms are bridged by two μ1,5-dicyanamide ligands. Variable temperature magnetic susceptibility measurements show the presence of ferromagnetic coupling in complex 2 with J = +26.20 cm-1 and antiferromagnetic coupling in complex 3 with J = -1.90 cm-1. © 2013 Elsevier Ltd. All rights reserved.

Three nickel(II) complexes derived from a tridentate NNO donor Schiff base ligand: Syntheses, crystal structures and magnetic properties

Two new nickel(II) complexes, [NiL(H 2O) 2Cl] (1) and [{NiLL′(H 2O)} 2(μ-H)]NO 3·H 2O (2), have been synthesized using a tridentate Schiff base ligand, HL, 2-[(2-dimethylamino-ethylimino)-methyl]-phenol, along with Cl - or NO 3 - as an anionic co-ligand or counter anion (where L′H = salicylaldehyde). Both complexes have been characterized by X-ray crystallography. The structural analyses reveal that complex 1 is mononuclear whereas 2 is a hydrogen-bridged dinuclear complex. The Ni(II) ions possess a distorted octahedral geometry in both structures. Both complexes show negative solvatochromic behaviour with increasing donor number (DN) of the solvent. In more coordinating solvents, like DMSO or methanol, the colour of the solutions is green, whereas in less coordinating solvents, like dichloromethane (DCM) or acetonitrile, it is red. © 2011 Elsevier Ltd. All rights reserved.

Complexes of NiX 2 (X = Cl - and NO 3 - ) with a NNO donor Schiff base: Anion dependent structural variations and spectroscopic behaviour

A new linear trinuclear nickel(II) complex, [Ni3(salme)2(OCn)4] (Hsalme = 2-[(3-methylamino-propylimino)-methyl]-phenol, OCn = cinnamate), showing weak ferromagnetic coupling (J = 1.8(1) cm-1) through phenoxo and a novel tridentate bridging mode (1κ2OO′:2κO′) of the cinnamate ligand has been synthesized and structurally characterized by X-ray crystallography. © 2009 Elsevier B.V.

Inorganic Chemistry Communications

A ferromagnetic linear trinuclear Ni(II)-Schiff base complex supported by phenoxo and cinnamato bridges

Three new trinuclear copper(II) complexes, [(CuL1) 3(μ3OH)][ClO4]23H2O (1), [(CuL2)3(μ3-OH)][ClO4] 2H2O (2), and [(CuL3) 3(μ3-OH)][ClO4]27H2O (3) have been synthesized from the three tridentate Schiff bases HL1, HL2, and HL3 (HL1 = 6aminomethyl-3-methyl-1- phenyl-4-azahex-2-en-1-one, HL2 = 6-aminoethyl-3methyl-1 -phenyl-4-azahex-2-en-1 -one, and HL3 = 6-aminodimethyl-3-methyl1- phenyl-4-azahex-2-en-1-one). They have been characterized by X-ray crystallography and IR and UV spectroscopy, and their magnetic properties have been investigated. All the compounds contain a partial cubane [Cu 3O4] core consisting of the trinuclear unit [(CuL) 3(μ3-OH)]2+, Perchlorate ions, and water molecules. In each of the complexes, the copper atoms are fivecoordinate with a distorted square-pyramidal geometry except complex 1, in which one of the CuII of the trinuclear unit is weakly coordinated to one of the Perchlorate ions. Magnetic measurements performed in SQUID MPMS-XL7 using polycrystalline samples at an applied field of 2 kOe indicate a global intramolecular ferromagnetic coupling. Magnetostructural correlations have been calculated on the basis of theoretical models without symmetry restriction. Continuous shape measurements are an appropriate tool for establishing the degree of distortion of the CuII from squareplanar geometry. Structural, theoretical, and experimental magnetic data indicate that the higher the degree of distortion, the greater the ferromagnetic coupling. © 2007 Wiley-VCH Verlag GmbH &amp; Co. KGaA.

Chemistry - A European Journal

Ferromagnetic coupling in trinuclear, partial cubane CuII complexes with a Î¼3-OH core: Magnetostructural correlations

Three di-Schiff-base ligands, N,N′-bis(salicylidene)-1,3-propanediamine (H2Salpn), N,N′-bis(salicylidene)-1,3-pentanediamine (H2Salpen) and N,N′-bis(salicylidine)-ethylenediamine (H2Salen) react with Ni(SCN)2 · 4H2O in 2:3 molar ratios to form the complexes; mononuclear [Ni(HSalpn)(NCS)(H2O)] · H2O (1a), trinuclear [{Ni(Salpen)}2Ni(NCS)2] (2b) and trinuclear [{Ni(Salen)}2Ni(NCS)2] (3) respectively. All the complexes have been characterized by elemental analyses, IR and UV-VIS spectra, and room temperature magnetic susceptibility measurements. The structures of 1a and 2b have been confirmed by X-ray single crystal analysis. In complex 1a, the Ni(II) atom is coordinated equatorially by the tetradentate, mononegative Schiff-base, HSalpn. Axial coordination of isothiocyanate group and a water molecule completes its octahedral geometry. The hydrogen atom attached to one of the oxygen atoms of the Schiff base is involved in a very strong hydrogen bond with a neighboring unit to form a centrosymmetric dimer. In 2b, two square planar [Ni(Salpen)] units act as bidentate oxygen donor ligands to a central Ni(II) which is also coordinated by two mutually cis N-bonded thiocyanate ligands to complete its distorted octahedral geometry. Complex 3 possesses a similar structure to that of 2b. A dehydrated form of 1a and a hydrated form of 2b have been obtained and characterized. The importance of electronic and steric factors in the variation of the structures is discussed. © 2007 Elsevier Ltd. All rights reserved.

Structural variations in Ni(II) complexes of salen type di-Schiff base ligands

Two tridentate Schiff bases, HL1(6-amino-3-methyl-1-phenyl-4-azahex-2-en-1-one), and HL2 (6-amino-3,6-dimethyl-1-phenyl-4-azahex-2-en-1-one) on reaction with Cu(II) perchlorate in the presence of triethyl amine yielded two new trinuclear copper(II) complexes, [(CuL1)3(μ3-OH)](ClO4) 2 (1) and [(CuL2)3(μ3-OH)](ClO4) 2 · 0.75H2O (2), whereas another tridentate ligand HL3 (7-amino-3-methyl-1-phenyl-4-azahept-2-en-1-one) underwent hydrolysis under the same reaction conditions to result in the formation of a mononuclear complex, [Cu(bn)(pn)ClO4] (3) [where bn = 1-benzoylacetonate and pn = 1,3-propanediamine]. All three complexes have been characterized by X-ray crystallography. For both 1 and 2 the cationic part is trinuclear with a [Cu3OH] core held by three carbonyl oxygen bridges between each pair of copper(II) atoms. The structure of 3 is a monomer with a chelating 1,3-propanediamine and a benzoyl acetone moiety. Magnetic measurements of 1 and 2 have been performed in the 2-300 K temperature range. The experimental data could be satisfactorily reproduced by using an isotropic exchange model, H = -J(S1S2 + S2S3 + S1S3), yielding as best fit parameters: J = -25.6 cm-1, g = 2.21 for 1 and J = -11.2 cm-1, g = 2.10 for 2. The EPR spectra at low temperature could be indicative of spin frustration in complex 1. © 2006 Elsevier Ltd. All rights reserved.

Trinuclear Cu(II) complexes containing peripheral ketonic oxygen bridges and a Î¼3-OH core: Steric influence on their structures and existence

A dinuclear NiII complex, [Ni2(L)2(H 2O)(NCS)2]·3H2O (1) in which the metal atoms are bridged by one water molecule and two μ2-phenolate ions, and a thiocyanato-bridged dimeric CuII complex, [Cu(L)NCS] 2 (2) [L = tridentate Schiffbase ligand, N-(3-aminopropyl) salicylaldimine, derived from 1:1 condensation of salicylaldehyde and 1,3-diaminopropane], have been synthesized and characterized by IR and UV/Vis spectroscopy, cyclic voltammetry and single-crystal X-ray diffraction studies. The structure of 1 consists of dinuclear units with crystallographic C 2 symmetry in which each NiII atom is in a distorted octahedral environment. The Ni-O distance and the Ni-O-Ni angle, through the bridged water molecule, are 2.240(11) Å and 82.5(5)°, respectively. The structure of 2 consists of dinuclear units bridged asymmetrically by di-μi1,3-NCS ions; each CuII ion is in a square-pyramidal environment with τ = 0.25. Variable-temperature magnetic susceptibility studies indicate the presence of dominant ferromagnetic exchange coupling in complex 1 with J = 3.1 cm-1, whereas complex 2 exhibits weak antiferromagnetic coupling between the CuII centers with J = -1.7 cm-1. © Wiley-VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2005.

European Journal of Inorganic Chemistry

Dinuclear complexes of MII thiocyanate (M = Ni and Cu) containing a tridentate schiff-base ligand: Synthesis, structural diversity and magnetic properties

Structural and magnetic studies of Schiff base complexes of nickel(ii) nitrite: Change in crystalline state, ligand rearrangement and a very rare Î¼-nitrito-1ÎºO:2ÎºN:3ÎºOâ€² bridging mode

Journal	Dalton Transactions
Publisher	-
ISSN	1477-9226
Open Access	No