Properties and X-ray crystal structures of copper(II) mixed complexes with thiodiacetate and 2,2′-bipyridyl or 2,2′:6′2″-terpyridyl

Abstract

Spectroscopic and structural investigations have been performed for two ternary complexes of copper(II), [Cu(bipy)(tda)(H₂O)]·4H₂O (1) and [Cu(terpy)(tda)](2)(bipy = 2,2′-bipyridyl, terpy = 2,2′:6′,2″-terpyridyl, and tda = thiodiacetate). Crystals of (1) are monoclinic, space group P2₁/c, with a = 11.136(7), b= 21.13(1), c= 8.999(6)Å, β= 113.2(2)°, and R= 0.057. Crystals of (2) are also monoclinic. space group C2/c, with a= 10.551(6), b= 21.23(1), c= 8.633(5)Å, β= 112.0(2)°, and R= 0.035. Complex (1) consists of [Cu-(bipy)(tda)(H₂O)] units connected by water molecules. The co-ordination polyhedron around the copper may be described as a distorted octahedron with the solphur atom and the water molecule in axial positions. Complex (2) consists of polymeric chains of Cu(terpy) units bridged by the tda ligand via the oxygens of the carboxylate groups. Consequently, the co-ordination polyhedron around the copper atom may be described as a distorted trigonal-bipyramidal arrangement. E.s.r. spectra confirm the crystallographic results for (1) both in the solid state and in solution. For (2). however, different e.s.r. spectra are obtained of the microcrystalline powder and of the solution. Only the powder spectrum agrees with a distorted trigonal-bipyramidal structure.