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

作者：Banerjee Ishita; Samanta Pabitra Narayan; Das Kalyan Kumar; Ababei Rodica; Kalisz Marguerite; Girard Adrien; Mathoniere Corine; Nethaji M; Clerac Rodolphe^*; Ali Mahammad

来源：Dalton Transactions, 2013, 42(5): 1879-1892.

DOI：10.1039/c2dt30983a

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%26apos;-Bu-t-biphenyl-3,4,3%26apos;,4%26apos;-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.

• 出版日期2013