Sulfate-bridged dimeric trinuclear copper(II)-pyrazolate complex with three different terminal ligands.

The reaction of CuSO4·5H2O, 4-chloro-pyrazole (4-Cl-pzH) and tri-ethyl-amine (Et3N) in di-methyl-formamide (DMF) produced crystals of di-aqua-hexa-kis-(μ-4-chloro-pyrazolato-κ(2) N:N')bis-(N,N-di-methyl-formamide)di-μ3-hydroxido-bis-(μ4-sulfato-κ(4) O:O':O'':O'')hexa-copper(II) N,N-di-methyl-formamide tetra-solvate dihydrate, [Cu3(OH)(SO4)(C3H2ClN2)3(C3H7NO)(H2O)]2·4C3H7NO·2H2O. The centrosymmetric dimeric molecule consists of two trinuclear copper-pyrazolate units bridged by two sulfate ions. The title compound provides the first example of a trinuclear copper-pyrazolate complex with three different terminal ligands on the Cu atoms, and also the first example of such complex with a strongly binding basal sulfate ion. Within each trinuclear unit, the Cu(II) atoms are bridged by μ-pyrazolate groups and a central μ3-OH group, and are coordinated by terminal sulfate, H2O and DMF ligands, respectively. Moreover, the sulfate O atoms coordinate at the apical position to the Cu atoms of the symmetry-related unit, providing square-pyramidal coordination geometry around each copper cation. The metal complex and solvent mol-ecules are involved in O-H⋯O hydrogen bonds, leading to a two-dimensional network parallel to (10-1).