Synthesis and catalytic activities of copper(II) complexes derived from a tridentate pyrazole-containing ligand. X-ray crystal structure of [Cu-2(mu-dpzhp-O,N,N ')(2)][Cu(MeOH)Cl-3](2)

The synthesis of the new tridentate ligand 1,3-bis(3,5-dimethylpyrazol-1-yl )propan-2-ol (Hdpzhp) and a number of its copper(II) complexes are describe d. The complexes, which have the form [Cu-2(mu -dpzhp-O,N,N')(2)]X-2 with X = Cu(MeOH)Cl-3, NO3, and BF4, and [Cu-2(mu -dpzhp-O,N,N')(mu -OH)Cl-2] hav e been characterized by elemental analysis, IR spectroscopy, ligand field a nd ESI mass spectrometry, showing the ligand to be dinucleating and to act as an N2O donor set with a bridging alkoxo group. The single-crystal X-ray structure Of [Cu-2(mu -dpzhp-O,N,N')(2)] [Cu(MeOH)Cl-3](2) shows the copper ions in the dinuclear cation in distorted square-planar environments of tw o oxygen and two nitrogen atoms from two different ligands with Cu-N distan ces of 1.932(7) to 1.992(6) Angstrom and with Cu-O distances of 1.873(6)-1. 976(6) Angstrom. Additionally, one chlorine of each anion is semicoordinate d to one of the two copper ions. Solid-state magnetic measurements show tha t the dinuclear unit is strongly antiferromagnetic, and paramagnetic in its CuCl3(MeOH) anions. The compound [Cu-2(mu -dpzhp-O,N,N')(2)](BF4)(2) is ca talytically active in the oxidative coupling of 2,6-dimethylphenol and lead s to a high selectivity in poly(1,4-phenylene ether) (PPE) over the unwante d side product, 4-(3,5-dimethyl-4-oxo-2,5-cyclohexadienylidene)-2,6-dimethy l-2,5-cyclohexadienone. (C) 2001 Elsevier Science B.V. All rights reserved.