Air oxygenation chemistry of 4-TBC catalyzed by chloro bridged dinuclear copper(II) complexes of pyrazole based tridentate ligands: synthesis, structure, magnetic and computational studies

Banerjee, Ishita and Samanta, Pabitra Narayan and Das, Kalyan Kumar and Ababei, Rodica and Kalisz, Marguerite and Girard, Adrien and Mathoniere, Corine and Nethaji, M and Clerac, Rodolphe and Ali, Mahammad (2013) Air oxygenation chemistry of 4-TBC catalyzed by chloro bridged dinuclear copper(II) complexes of pyrazole based tridentate ligands: synthesis, structure, magnetic and computational studies. In: DALTON TRANSACTIONS, 42 (5). pp. 1879-1892.

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Abstract

Four dinuclear bis(mu-Cl) bridged copper(II) complexes, Cu-2(mu-Cl)(2)(L-X)(2)](ClO4)(2) (L-X = N,N-bis(3,5-dimethylpyrazole-1-yl)-methyl]benzylamine with X = H(1), OMe(2), Me(3) and Cl(4)), have been synthesized and characterized by the single crystal X-ray diffraction method. In these complexes, each copper(II) center is penta-coordinated with square-pyramidal geometry. In addition to the tridentate L-X ligand, a chloride ion occupies the last position of the square plane. This chloride ion is also bonded to the neighboring Cu(II) site in its axial position forming an SP-I dinuclear Cu(II) unit that exhibits small intramolecular ferromagnetic interactions and supported by DFT calculations. The complexes 1-3 exhibit methylmonooxygenase (pMMO) behaviour and oxidise 4-tert-butylcatechol (4-TBCH2) with molecular oxygen in MeOH or MeCN to 4-tert-butyl-benzoquinone (4-TBQ), 5-methoxy-4-tert-butyl-benzoquinone (5-MeO-4-TBQ) as the major products along with 6,6'-Bu-t-biphenyl-3,4,3',4'-tetraol and others as minor products. These are further confirmed by ESI- and FAB-mass analyses. A tentative catalytic cycle has been framed based on the mass spectral analysis of the products and DFT calculations on individual intermediates that are energetically feasible.

Item Type:	Journal Article
Publication:	DALTON TRANSACTIONS
Publisher:	ROYAL SOC CHEMISTRY
Additional Information:	Copyright for this article belongs to ROYAL SOC CHEMISTRY, ENGLAND
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	28 Feb 2013 08:32
Last Modified:	28 Feb 2013 08:32
URI:	http://eprints.iisc.ac.in/id/eprint/45854

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