Magnetic properties of dinuclear copper(II) complexes with simple pyrazolate bridges
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Three new copper(II) complexes with simple pyrazolate bridges have been prepared, [Cu-2(pz)(2)(dpa)(2)(H2O)Cl]Cl . H2O 1, [Cu-2(pz)(2)(phen)(2)Cl-2]. 2C(2)H(5)OH 2 and [Cu-2(pz)(phen)(2)Cl-3]. 2H(2)O 3 (Hpz = pyrazole, dpa = di(2-pyridyl)amine, phen = 1,10-phenanthroline) and their crystal and molecular structures determined. The copper centres in the binuclear cation in 1 have a square pyramidal geometry at Cu1 and a distorted octahedral geometry at Cu2. The neutral complexes 2 and 3 have the copper atoms in a distorted square pyramidal geometry. Complexes 1 and 2 are bibridged by pyrazolate while 3 is monobridged by this ligand. Variable temperature magnetic studies on all three complexes indicate the existence of antiferromagnetic exchange phenomena (-2J = 191, 169, 42 cm(-1) for 1, 2 and 3 respectively). Extended Huckel calculations showed a HOMO/LUMO gap which is in agreement with the experimental data.
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