title: New phenoxido-bridged quasi-tetrahedral and rhomboidal [Cu4] compounds bearing μ4-oxido or μ(1,1)-azido ligands: synthesis, chemical reactivity, and magnetic studies.
abstract: [Cu(2)(μ(4)-O)Cu(2)] and [Cu(2)(μ(1,1)-N(3))(4)Cu(2)] geometrical arrangements are found in a new family of tetranuclear copper(II) complexes: [Cu(4)(μ(4)-O)(μ-cip)(2)Cl(4)] (1), [Cu(4)(μ(4)-O)(μ-cip)(2)(μ(1,3)-O(2)CPh)(4)]·2CH(3)OH (2·2CH(3)OH), and [Cu(4)(μ(1,1)-N(3))(4)(μ-cip)(2)(N(3))(2)]·DMF (3·DMF) [Hcip = 2,6-bis(cyclohexyliminomethylene)-4-methylphenol; CH(3)OH = methanol; DMF = dimethylformamide]. These complexes have been characterized by X-ray crystallography, and their magnetic properties have been studied. 1 and 2 form quasi-tetrahedral [Cu(4)(μ(4)-O)] complexes, and 3 is the first example of a rhomboidal [Cu(4)(μ(1,1)-N(3))] compound. Formation of the [Cu(4)] compounds is achieved via ligand-exchange reactions. The relative binding strength of the three ancillary ligands as N(3)(-) > PhCO(2)(-) > Cl(-) has been demonstrated from the core-conversion and peripheral ligand-exchange reactions. For the three complexes, the magnetic susceptibility measurements in the range of 1.8-300 K have been performed and modeled using two isolated S = (1)/(2) dimers based on the spin Hamiltonian H = -2J{S(Cu,1)·S(Cu,2)} with J/k(B) = -513, -340, and -315 K for 1-3, respectively (where J is the exchange constant through the oxido-phenoxido and azido-phenoxido bridges, respectively).
authors.affiliation: Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India.
authors.forename: Mrinal
authors.initials: M
authors.lastname: Sarkar
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Clérac
authors.forename: Corine
authors.initials: C
authors.lastname: Mathonière
authors.forename: Nigel G R
authors.initials: NG
authors.lastname: Hearns
authors.forename: Valerio
authors.initials: V
authors.lastname: Bertolasi
authors.forename: Debashis
authors.initials: D
authors.lastname: Ray
mesh_terms: D001386:Azides / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008024:Ligands; D008280:Magnetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D001386:Azides; D008024:Ligands; D009942:Organometallic Compounds; D003300:Copper; D010100:Oxygen