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.

ASHUTOSH GHOSH

Chemistry

P MUKHERJEE

V TANGOULIS

M ESTRADER

C DIAZ

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

A new dinuclear Ni(II) complex [Ni2L2(PhCOO)(H2O)2]ClO4 (1) has been synthesized by reacting Ni(ClO4)2·6H2O with a reduced Schiff base ligand [(3-dimethylamino-propylamino)-methyl]-phenol (HL) in presence of benzoic acid in 1:1:1 ratios. Structural analysis reveals that complex 1 is a di-μ2-phenoxo-bridged dinuclear Ni(II) complex and has an additional syn-syn benzoate bridge. Enzyme kinetic studies reflect that it (1) is effective in mimicking catecholase like activity with 3,5-di-tert-butylcatechol (3,5-DTBC) as the substrate. Kinetic measurements suggest that the rate of catechol oxidation follows first order kinetics with respect to the catalyst. The possible intermediates during the course of reaction are identified from ESI–MS spectra. The characteristic EPR spectra of the complex in the presence of 3,5-DTBC supports the formation of nickel(II)-semiquinonate as an intermediate species during the catalytic oxidation. When the synthesis is carried out with Ni(II) : HL ratio of 3:2, a different compound [Ni3L2(PhCOO)4] (2) is produced incorporating an additional Ni(II)-benzoate. 2 possesses a linear trinuclear structure with the tridentate reduced Schiff base ligand coordinated to the terminal nickel atoms which are linked to the central Ni(II) by phenoxo and carboxylate bridges. Unlike 1, it does not show any catalytic activity towards catechol oxidation. Variable temperature magnetic susceptibility measurements have also been performed for 1 and 2. Complex 1 indicates the presence of intradimer antiferromagnetic interactions (J = −5.65 cm−1). In contrast to complex 1, ferromagnetic coupling (J = 3.55 cm−1) is observed in complex 2. © 2016 Elsevier B.V.

Journal of Molecular Catalysis A: Chemical

Deactivation of catecholase-like activity of a dinuclear Ni(II) complex by incorporation of an additional Ni(II)

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.

Dalton Transactions

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

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.

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

Two new nickel(ii) complexes [Ni2L2(PhCOO) 2(H2O)] (1), [Ni2L2(PhCH 2COO)2(H2O)] (2) have been synthesized using a tridentate Schiff base ligand, HL (2-[(3-dimethylamino-propylimino)-methyl]- phenol) and the carboxylate monoanions, benzoate and phenylacetate, respectively. The complexes have been characterized by spectral analysis, variable temperature magnetic susceptibility measurement and crystal structure analysis. The structural analyses reveal that both complexes are dinuclear in which the distorted octahedral Ni2+ ions share a face, bridged by one water molecule and two μ2-phenoxo oxygen atoms. A monodentate benzoate or phenylacetate anion and two nitrogen atoms of the chelating deprotonated Schiff base (L) complete the hexa-coordination around the metal ion. Variable-temperature magnetic susceptibility studies indicate the presence of dominant ferromagnetic exchange coupling in complexes 1 and 2 with J values of 11.1(2) and 10.9(2) cm-1 respectively. An attempt has been made to rationalize the observed magneto-structural behavior considering the importance of the additional water bridge in the present two complexes and also in other similar species. © 2011 The Royal Society of Chemistry.

The importance of an additional water bridge in making the exchange coupling of bis(Î¼-phenoxo) dinickel(ii)complexes ferromagnetic

Four new nickel(II) complexes, [Ni2L2(NO2)(2)]center dot CH2Cl2 center dot C2H5OH, 2H(2)O (1), [Ni2L2(DMF)(2)(mu-NO2)]ClO4 center dot DMF (2a), [Ni2L2(DMF)(2)(mu-NO2)]ClO4 (2b) and [Ni3L'(2)(mu(3)-NO2)(2)(CH2Cl2)](n)center dot 1.5H(2)O (3) where HL = 2-[(3-amino-propylimino)-methyl]-phenol, H2L' = 2-({3-[(2-hydroxy-benzylidene)-amino]-propylimino}-methyl)-phenol and DMF = N,N-dimethylformamide, have been synthesized starting with the precursor complex [NiL2]center dot 2H(2)O, 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-mu(2)-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-(mu-nitrito-1 kappa O:2 kappa N) bridge is present in addition to the di-mu(2)-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 m-nitrito-1 kappa O:2 kappa N bridged trinuclear units are linked through a very rare mu(3)-nitrito-1 kappa O:2 kappa N:3 kappa O' 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.

Structural and magnetic studies of Schiff base complexes of nickel(II) nitrite: change in crystalline state, ligand rearrangement and a very rare mu-nitrito-1 kappa O:2 kappa N:3 kappa O ' bridging mode

A linear trinuclear Ni-Schiff base complex [Ni 3 (salpen) 2(PhCH 2COO) 2(EtOH)] has been synthesized by combining Ni(ClO 4) 2 · 6H 2O, phenyl acetic acid (C 6H 5CH 2COOH), and the Schiff base ligand, N,N′-bis(salicylidene)-1,3- pentanediamine (H 2salpen). This complex is self-assembled through hydrogen bonding and C-H-π interaction in the solid state to generate a sheet-like architecture, while in organic solvent (CH 2Cl 2), it forms vesicles with a mean diameter of 290 nm and fused vesicles, depending upon the concentration of the solution. These vesicles act as an excellent carrier of dye molecules in CH 2Cl 2. The morphology of the complex has been determined by scanning electron microscopy and transmission electron microscopy experiments, and the encapsulation of dye has been examined by confocal microscopic image and electronic absorption spectra. © 2009 American Chemical Society.

Inorganic Chemistry

Solvent-assisted formation of vesicles by a self-assembling Ni 3-schiff base complex

Structural and magnetic characterization of compound {[Ni 2(L)2(OAc)2][Ni3(L) 2(OAc)4]}-2CH3CN (3) (HL = the tridentate Schiff base ligand, 2-[(3-methylamino-propylimino)-methyl]-phenol) shows that it is a rare example of a crystal incorporating a dinuclear Ni(ll) compound, [Ni2(L)2(OAc)2], and a trinuclear one, [Ni 3(L)2(OAc)4]. Even more unusual is the fact that both Ni (II) complexes, [Ni2(L)2(OAc)2] (1) and [Ni3(L)2(OAc)4(H2O) 2] · CH2Cl2· 2CH3OH (2), have also been isolated and structurally and magnetically characterized. The structural analysis reveals that the dimeric complexes [Ni 2(L)2(OAc)2] in cocrystal 3 and in compound 1 are almost identical-in both complexes, the Ni(ll) ions possess a distorted octahedral geometry formed by the chelating tridentate ligand (L), a chelating acetate ion, and a bridging phenoxo group with very similar bond angles and distances. On the other hand, compound 2 and the trinuclear complex in the cocrystal 3 show a similar linear centrosymmetric structure with the tridentate ligand coordinated to the terminal Ni(ll) and linked to the central Ni(ll) by phenoxo and carboxylate bridges. The only difference is that a water molecule found in 2 is not present in the trinuclear unit of complex 3; instead, the coordination sphere is completed by an additional bridging oxygen atom from an acetate ligand. Variable-temperature (2-300 K) magnetic susceptibility measurements show that the dinuclear unit is antiferromagnetically coupled in both compounds (2J= -36.18 and -29.5 cm-1 in 1 and 3, respectively), whereas the trinuclear unit shows a very weak ferromagnetic coupling in compound 3 (2J= 0.23 cm-1) and a weak antiferromagnetic coupling in 2 (2J= -8.7(2) cm-1) due to the minor changes in the coordination sphere. © 2009 American Chemical Society.

(Ni2), (Ni3), and (Ni2 + Ni3): A unique example of isolated and cocrystallized Ni2 and Ni 3 complexes

Two tridentate N,N,O donor Schiff bases, HL1 (4-(2-ethylamino-ethylimino)-pentan-2-one) and HL2 (3-(2-amino-propylimino)-1-phenyl-butan-1-one) on reaction with CuII acetate in presence of triethyl amine yielded two basal-apical, mono-atomic acetate oxygen-bridging dimeric copper(II) complexes, [Cu2L12(OAc)2] (1), [Cu2L22(OAc)2] (2). Whereas two other similar tridentate ligands HL3 (4-(2-amino-propylimino)-pentane-2-one) and HL4 (3-(2-amino-ethylimino)-1-phenyl-butan-1-one) under the same conditions produced a mixture of the corresponding dimers and a one-dimensional alternating chain of the dimer and copper acetate moiety, [Cu4L32(OAc)6]n (3) and [Cu4L42(OAc)6]n (4), formed by a very rare μ3 bridging mode of the acetate ion. All four complexes (1-4) have been characterized by X-ray crystallography. The isotropic Hamiltonian, H = -JS1S2 has been used to interpret the magnetic data. Magnetic measurements of 1 and 2 in the temperature range 2-300 K reveal a very weak antiferromagnetic coupling for both complexes (J = -0.56 and -1.19 cm-1 for 1 and 2, respectively). © 2008 Elsevier Ltd. All rights reserved.

Polyhedron

CuII acetate complexes involving N,N,O donor Schiff base ligands: Mono-atomic oxygen bridged dimers and alternating chains of the dimers and Cu2(OAc)4

Formation of a quasi-symmetrical μ3-carbonato-bridged self-assembled heteromolecular triangle of Ni(II), [(μ3-CO 3){Ni2(salmeNH)2(NCS)2} {Ni(salmeNH2)2]·Et2O·H 2O (HsalmeNH = 2-[(3-methylamino-propylimino)-methyl]-phenol) involves atmospheric CO2 uptake in a neutral medium, by spontaneous self-reorganization of the starting mononuclear Ni(II)-Schiff-base complex, [Ni(salmeNH)2]. The environment around Ni(II) in two of the subunits is different from the third one. The starting complex, [Ni(salmeNH) 2], and one of the possible intermediate species, [Ni(salmeNH 2)2(NCS)2], which has a very similar coordination environment to that in the third Ni(II) center, have been characterized structurally. A plausible mechanism for the formation of such a triangle has also been proposed. The compound shows a very strong antiferromagnetic coupling. Fit as a regular triangular arrangement gave J = -53.1, g = 2.24, and R = 1.5 × 10-4. © 2008 American Chemical Society.

Journal	Data powered by TypesetInorganic Chemistry Communications
Publisher	Data powered by TypesetELSEVIER SCIENCE BV
ISSN	1387-7003
Open Access	No