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Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/3405
Title: Copper(II) azide complexes of alipathic and aromatic amine based tridentate ligands: Novel structure, spectroscopy, and magnetic properties
Authors: Manikandan P.
Muthukumaran R.
Thomas K.R.J.
Varghese B.
Chandramouli G.V.R.
Manoharan P.T.
Published in: Inorganic Chemistry
Abstract: Copper(II) azide complexes of three tridentate ligands namely 2,6-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L), 2,6-(pyrazol-1-ylmethyl)pyridine (L′), and dipropylenetriamine (dpt) yield three kinds of complexes with different azide-binding modes. The ligand L forms two end-on-end (μ-1,3) diazido-bridged binuclear complexes, [CuL-(μ-N3)]2(ClO4)2 (1) and [CuL(μ-N3)(ClO4)]2•2CH3CN (2), and L′ forms a perchlorato-bridged quasi-one-dimensional chain complex, [CuL′(N3)(ClO4)]n (3) with monodentate azide coordination. The ligation of dipropylenetriamine (dpt) gives a end-on (μ-1,1) diazido-bridged binuclear copper complex [Cu(dpt)(μ-N3)]2(ClO4)2 (4). The crystal and molecular structures of these complexes have been solved. Variable-temperature EPR results of 1 and 2 are identical and indicate the presence of both ferromagnetic and antiferromagnetic interactions within the dimer, the former dominating at low temperatures and the latter at high temperatures. The unusual temperature-dependent magnetic moment and EPR spectra of this dimer reveal the presence of temperature-dependent population of two triplet states, one being caused by antiferromagnetic and the other by ferromagnetic interaction, the former transforming to the latter on cooling. While the interaction of ground spin doublets of the two metal centers gives rise to a ferromagnetic coupling of Jg = 90.73 cm-1, the other coupling of Je = -185.64 cm-1 is suggested to be caused by the interaction between an electron in one metal center and an electron from the azide of the other monomer by excitation of a d-electron to the empty ligand orbital. The ferromagnetic state is energetically favored by 104.39 cm-1. Compound 3 exhibits axial spectra at room temperature and 77 K, and variable-temperature magnetic susceptibility data indicate that the copper centers form a weakly antiferromagnetic one-dimensional chain with J = -0.11 cm-1. In the case of 4, the unique presence of two nonidentical dimeric units with different bond lengths and bond angles within the unit cell as inferred by crystal structure is proved by single-crystal EPR spectroscopy.
Citation: Inorganic Chemistry (2001), 40(10): 2378-2389
URI: https://doi.org/10.1021/ic0009223
http://repository.iitr.ac.in/handle/123456789/3405
Issue Date: 2001
ISSN: 201669
Author Scopus IDs: 55767788400
54887230100
57203389297
14016867200
55375578100
15120961900
Author Affiliations: Manikandan, P., Department of Chemistry, Regional Sophisticated Instrumentation Centre, Indian Institute of Technology Madras, Chennai-600 036, India
Muthukumaran, R., Department of Chemistry, Regional Sophisticated Instrumentation Centre, Indian Institute of Technology Madras, Chennai-600 036, India
Thomas, K.R.J., Department of Chemistry, Regional Sophisticated Instrumentation Centre, Indian Institute of Technology Madras, Chennai-600 036, India
Varghese, B., Department of Chemistry, Regional Sophisticated Instrumentation Centre, Indian Institute of Technology Madras, Chennai-600 036, India
Chandramouli, G.V.R., Department of Chemistry, Regional Sophisticated Instrumentation Centre, Indian Institute of Technology Madras, Chennai-600 036, India
Manoharan, P.T., Department of Chemistry, Regional Sophisticated Instrumentation Centre, Indian Institute of Technology Madras, Chennai-600 036, India
Corresponding Author: Manoharan, P.T.; Department of Chemistry, Reg. Sophisticated Instrumen. Centre, Indian Inst. of Technology Madras, Chennai-600 036, India; email: ptm@magnet.iitm.ernet.in
Appears in Collections:Journal Publications [CY]

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