Transition metal complexes with ‘end-off’ compartmental Schiff bases containing sulphonic or phosphonic groups

Abstract

Nickel(II), manganese(II) and copper(II) complexes with ‘end-off’ compartmental ligands derived from 2,6-diformyl-4-chlorophenol and α or β-amino-sulphonic or aminophosphonic acids, have been prepared. The mono- and homobinuclear complexes, obtained by template or step by step procedures, have been characterized by IR, UV, scanning electron microprobe analysis and magnetic susceptibility measurements. The electrochemical behaviour of some complexes has been also examined. The crystal structure of {[Cu 2(C 10H 8ClN 2O 7S 2)(OH)](DMSO(H 2O)} 2 has been determined by X-ray crystallography. The compound is orthorhombic, space group Pbca, with a=17.071(5), b=11.751(5), c=20.464(4) Å, Z=4. The molecule of the compound is centrosymmetric. One five-coordinate square pyramidal and one four-coordinate square planar copper atom are present in the asymmetric unit, and the four coordinate copper also makes a contact of 2.58 Å with a DMSO molecule. Selected bond distances are: CuO (bridging) 1.95 Å (mean), CuO (base) 2.00 Å, CuN (base) 1.96 Å (mean), CuO (axial) 2.25 Å. The organic ligand is pentadentate; the hydroxo oxygen atom is bridging two copper atoms of the same asymmetric unit and is axially bonded to one copper atom of the centrosymmetric unit. The clathrate water molecules are hydrogen bonded to the compound.