Nickel(II) induced cleavage of the iminic pendant arm in unsymmetrical Schiff base compartmental ligands

Adams, Harry; Clunas, Scott; Fenton, David E.

doi:10.1016/s1387-7003(01)00305-7

Cited by 14 publications

(8 citation statements)

References 6 publications

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“…The coordination around the nickel atom is completed by an oxygen atom of a water molecule, which acts as a bridge between the two metal atoms. Therefore, both nickel atoms are linked through a triple oxygen bridge, leading to a Ni−Ni distance of 2.9126(15) Å, which is close to those found in other similar dinuclear nickel(II) complexes. − …”

Section: Resultssupporting

confidence: 77%

“…Finally, the Ni−N amine bond distances [Ni(1)−N(1) = 2.057(7) Å; Ni(2)−N(3) = 2.053(7) Å] to the pendant arm are shorter than the Ni−N bond lengths [Ni(1)−N(2) = 2.157(7) Å; Ni(2)−N(4) = 2.163(7) Å] of the other amine donor. However, both distances are within the normal range observed in other hexacoordinate nickel(II) complexes of amine ligands [2.048−2.134 Å]. − …”

Section: Resultssupporting

confidence: 69%

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Coordination Chemistry of Amine Bis(phenolate) Cobalt(II), Nickel(II), and Copper(II) Complexes

et al. 2006

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Cobalt(II), nickel(II), and copper(II) (1, 2, and 3) complexes of the dianionic form of the bis(phenolate) ligand N,N-bis(3,4-dimethyl-2-hydroxybenzyl)-N',N'-dimethylethylenediamine (H2L) have been synthesized by electrochemical oxidation of the appropriate metal in an acetonitrile solution of the ligand. When copper is used as the anode, the addition of 1,10-phenanthroline to the electrolytic phase gave rise to a different compound [CuL]2.2CH3CN (4). The compounds [CoL]2.2CH3CN (1), [Ni2L2(H2O)].H2O (2), [CuL]2.3H2O (3), and [CuL]2.2CH3CN (4) were characterized by microanalysis, IR, electronic spectroscopy, FAB mass spectrometry, magnetic measurements and by single-crystal X-ray diffraction. The crystal structures show that the complexes have a dinuclear structure. In compounds 1, 3, and 4, two metal ions are coordinated by the two amine nitrogens and the two phenol oxygen atoms of a deprotonated pendant phenol ligand, with one phenolic oxygen atom from ligand acting as a bridge. In compounds 1 and 3, each metal center has a geometry that is closest to trigonal bipyramidal. Magnetic susceptibility data for both compounds show an antiferromagnetic coupling with 2J = -15 cm(-1) for the cobalt(II) complex and a strong antiferromagnetic coupling with 2J = -654 cm(-1) for the copper(II) complex. However, in 4 the geometry around the metal is closer to square pyramidal and the compound shows a lower antiferromagnetic coupling (2J = -90 cm(-1)) than in 3. The nickel atoms in the dimeric compound 2 are hexacoordinate. The NiN2O4 chromophore has a highly distorted octahedral geometry. In this structure, a dianionic ligand binds to one nickel through the two amine nitrogen atoms and the two oxygen atoms and to an adjacent nickel via one of these oxygen atoms. The nickel atoms are linked through a triple oxygen bridge involving two phenolic oxygens, each from a different ligand, and an oxygen atom from a water molecule. The two nickel ions in 2 are ferromagnetically coupled with 2J = 19.8 cm(-1).

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Section: Resultssupporting

confidence: 77%

Section: Resultssupporting

confidence: 69%

Coordination Chemistry of Amine Bis(phenolate) Cobalt(II), Nickel(II), and Copper(II) Complexes

et al. 2006

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“…As such, it can be considered that Ni( 1 46 The nickel atoms are separated by 3.2076(13) A ˚, a distance that is close to those found in other similar dinuclear nickel compounds. [47][48][49] The Ni(1)-O(5) bond distance [2.096(3) A ˚] is as expected and is similar to those described above. However, the Ni(2)-O(6) bond distance [2.328(7) A ˚] is considerably longer and this is indicative of a weak interaction between the two atoms.…”

Section: Structure Of [Ni 2 L 2 (H 2 O) 15 ]•Ch 3 Cn (3)supporting

confidence: 76%

Electrochemical synthesis and structural characterization of Co(II), Ni(II) and Cu(II) complexes of N,N-bis(4,5-dimethyl-2-hydroxybenzyl)-N-(2-pyridylmethyl)amine

et al. 2009

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The electrochemical oxidation of anodic metal (cobalt, nickel or copper) in a cell containing an acetonitrile solution of the ligand N,N-bis(4,5-dimethyl-2-hydroxybenzyl)-N-(2-pyridylmethyl)amine (H2L) affords complexes [Co2L2].H2O (1), [Ni3L3] (2) and [Cu2L2] 3H2O (4). On using nickel as the anode and the addition to the solution electrolytic phase of the amount of water necessary to saturate the solution, the electrolytic process gave rise to the new compound [Ni2L2(H2O)1.5].CH3CN (3). Compounds 1 and 4 are dimeric and the metal atoms are pentacoordinated. Compound 3 also consists of dimeric neutral molecules with the nickel atoms in both penta- and hexacoordinated environments. The crystal structure of shows the presence of a trimeric compound in which the nickel atoms are hexacoordinated. Electronic, IR and FAB spectra of the complexes are discussed and related to the structural information. The magnetic behavior of 1-4 denotes the occurrence of intramolecular antiferromagnetic interactions. The values obtained for the coupling constant J are -4.2 cm(-1), -5.3 cm(-1), -30 cm(-1) and -4.7 cm(-1) for 1, 2, 3 and 4, respectively. These values are in full agreement with the structural characteristics of the compounds. The catalytic activity of the complexes towards the decomposition of hydrogen peroxide (catalase activity) was also studied.

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“…10 It was anticipated that in the corresponding reactions with nickel() perchlorate a bioresemblant Ni-OH-Ni bridge would be formed however with HL 1 -HL 3 hydrolytic cleavage of the pendant imine. 10, 11 As the reactions of HL 1 -HL 3 with nickel() acetate in the presence of a coordinating anion such as the isothiocyanate anion [NCS Ϫ ] had provided dinuclear nickel() complexes in which the ligand remains intact 12 it was proposed that the criteria for cleavage of the iminic pendant arm in metal complexes of unsymmetrical Schiff base compartmental ligands are the presence of both weakly or non-coordinating anions (ClO 4 Ϫ , BF 4 Ϫ ) and nickel() cations. It was also suggested that the reaction proceeded through the activation of coordinated water at a nickel() ion or by initial formation of a hydroxo bridge at the dinickel centre.…”

Section: Introductionmentioning

confidence: 99%

Dinuclear nickel(ii) complexes of reduced asymmetric compartmental ligandsIn memoriam Noel McAuliffe (1941–2002).

et al. 2003

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Nickel(II) induced cleavage of the iminic pendant arm in unsymmetrical Schiff base compartmental ligands

Cited by 14 publications

References 6 publications

Coordination Chemistry of Amine Bis(phenolate) Cobalt(II), Nickel(II), and Copper(II) Complexes

Coordination Chemistry of Amine Bis(phenolate) Cobalt(II), Nickel(II), and Copper(II) Complexes

Electrochemical synthesis and structural characterization of Co(II), Ni(II) and Cu(II) complexes of N,N-bis(4,5-dimethyl-2-hydroxybenzyl)-N-(2-pyridylmethyl)amine

Dinuclear nickel(ii) complexes of reduced asymmetric compartmental ligandsIn memoriam Noel McAuliffe (1941–2002).

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