Bis-(5,5? Copper(II) and Cadmium(II) Complexes with Ethylenediamine. Synthesis, Crystal Structures, Spectroscopic and Thermal Characterization of Cis-[Cu(Barb)2(En)] and {[Cd(Barb) 2(?-En)]·2H2O}n

Abstract

Two new bis(5,5′-diethylbarbiturato) (barb) complexes of copper(II) and cadmium(II) with ethylenediamine (en) were synthesized and characterized by elemental analysis, FT-IR spectroscopy and thermal analysis. In addition, their solid-state structures were determined by single crystal X-ray diffraction studies, cis-[Cu(barb)<inf>2</inf>(en)] (1) crystallizes in the monoclinic space group of C2/c and consists of neutral monomeric units, in which the copper(II) ion exhibit a highly distorted octahedral coordination by two barb anions and a neutral chelating en ligand. The individual molecules of 1 are held together by N-H⋯O hydrogen bonds, forming a three-dimensional network. {[Cd(barb)<inf>2</inf>(μ-en)]·2H<inf>2</inf>O}<inf>n</inf> (2) is a one-dimensional coordination polymer and also crystallizes in the monoclinic crystal system (P2<inf>1</inf>/c). In 2, [Cd(barb)<inf>2</inf>(en)] building blocks are connected into a chain by bridging NH<inf>2</inf> groups of en, and the individual chains are further stacked by O-H⋯O and N-H⋯O hydrogen bonds to form a three-dimensional supramolecular framework. The barb ligands in both complexes act as a bidentate ligands via the negatively charged imino N atom and one of the carbonyl O atoms adjacent to the imino N atom. The M-O bond distances in both complexes are much longer than M-N bond distances, indicating a weak interaction of the carbonyl group of barb. © 2005 Wiley-VCH Verlag GmbH & Co. KGaA.