Synthesis and characterization of dinuclear copper(II) complexes. Crystal structure of aquatrichlorohydroxo-3,6-bis(2′-pyridyl)pyridazinedicopper(II)

Abstract

The tetradentate ligand 3,6-biz(2′-pyridazine (I) forms with copper(II) chloride the dinuclear complexes Cu 2LCl 4 (2), Cu 2LCl 3(OH)· 1 2 H 2O (3) and Cu 2LCl 3(OH)(H 2O) (4), depending on the reaction conditions. By treatment with water, 2 and 3 transform into 4. The crystal structure of 4 has been determined by X-ray methods: it crystallizes in the triclinic space group P 1 , with two molecules in a unit cell of dimensions a = 10.240(7), b = 11.245(9), c = 8.521(6) Å, α = 90.0(1), β = 114.1(1), γ = 102.3(1)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.053 for 2887 observed reflections. The structure consists of dinuclear complexes, in which the copper atoms, bridged by the hydroxyl group and by the pair of nitrogen atoms of pyridazine moiety, are in a square pyramidal arrangement. Each basal coordination is completed by one pyridyl nitrogen atom from the ligand and by one chlorine atom; the apices of the pyramids are occupied by a chlorine atom and a water molecule, which, on the same side with respect to the basal coordination planes, are involved in an intramolecular hydrogen bond.