title: 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.
abstract: Four dinuclear bis(μ-Cl) bridged copper(II) complexes, [Cu(2)(μ-Cl)(2)(L(X))(2)](ClO(4))(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-TBCH(2)) 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.
authors.affiliation: Department of Chemistry, Jadavpur University, Kolkata 700 032, India.
authors.forename: Ishita
authors.initials: I
authors.lastname: Banerjee
authors.forename: Pabitra Narayan
authors.initials: PN
authors.lastname: Samanta
authors.forename: Kalyan Kumar
authors.initials: KK
authors.lastname: Das
authors.forename: Rodica
authors.initials: R
authors.lastname: Ababei
authors.forename: Marguerite
authors.initials: M
authors.lastname: Kalisz
authors.forename: Adrien
authors.initials: A
authors.lastname: Girard
authors.forename: Corine
authors.initials: C
authors.lastname: Mathonière
authors.forename: M
authors.initials: M
authors.lastname: Nethaji
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Clérac
authors.forename: Mahammad
authors.initials: M
authors.lastname: Ali
mesh_terms: D000388:Air; D002384:Catalysis; D002396:Catechols / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D007700:Kinetics; D008024:Ligands; D008280:Magnetics; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000378:metabolism; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D011720:Pyrazoles / Q000737:chemistry
chemical_list: D002396:Catechols; D056831:Coordination Complexes; D008024:Ligands; D011720:Pyrazoles; C038096:tert-butylcatechol; C031280:pyrazole; D003300:Copper; D006899:Mixed Function Oxygenases; C027635:3,5-dimethylpyrazole