Synthesis, X-ray structure and properties of a new nitrite-bound copper(II) complex with 2-(3,5- dimethylpyrazol-1-ylmethyl)pyridine in a CuN4(O) coordination

Lal, Tapan Kumar ; Richardson, John F. ; Mashuta, Mark S. ; Buchanan, Robert M. ; Mukherjee, Rabindra Nath (1997) Synthesis, X-ray structure and properties of a new nitrite-bound copper(II) complex with 2-(3,5- dimethylpyrazol-1-ylmethyl)pyridine in a CuN4(O) coordination Polyhedron, 16 (24). pp. 4331-4336. ISSN 0277-5387

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S02775...

Related URL: http://dx.doi.org/10.1016/S0277-5387(97)00201-5

Abstract

Synthesis and characterization of a nitrite-bound copper(II) compound [CuL4)2(ONO)]ClO4 have been achieved (L4 = 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine]. The bidentate ligand L4 provides a pyridine and a pyrazole donor site; however, they are separated by a methylene spacer. The complex has been structurally characterized and it belongs to only a handful of complexes having nitrito-bound mononuclear copper(II) centre. The metal atom has a distorted square pyramidal geometry with the copper atom displaced from the equatorial plane by 0.25 Å. In MeCN solution the green complex exhibits a broad ligand-field transition at 655 nm with a shoulder at 675 nm and in dichloromethane-toluene glass (80 K) it exhibits an EPR spectral feature characteristic of the unpaired electron in the dx2-y2 orbital. Variable-temperature (80-300 K) magnetic susceptibility measurements in the solid state as well as room temperature measurement in MeCN solution reveal mononuclear magnetically dilute copper(II) centre. When examined by cyclic voltammetry (MeCN solution) it displays electrochemically irreversible CuII---CuI response [cathodic peak potential, Epc (V vs saturated calomel electrode (SCE)): -0.32]. An oxidative response is observed at 1.14 V, probably due to bound-nitrite oxidation and is partially removed to generate a solvated complex at the electrode surface. The latter species gives rise to reversible CuII---CuI redox response [ E½ =0.41 V vs SCE].

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine; Nitrite-bound Copper(II) Complexes; X-ray Structure; Cyclic Voltammetry; EPR Spectra; Absorption Spectra; Magnetism
ID Code:25994
Deposited On:04 Dec 2010 10:43
Last Modified:03 Mar 2011 08:41

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