Bis–(5,5′–diethylbarbiturato) 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(μ–en)]·2H2O}n

Abstract

AbstractTwo 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)2(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)2(μ–en)]·2H2O}n (2) is a one–dimensional coordination polymer and also crystallizes in the monoclinic crystal system (P21/c). In 2, [Cd(barb)2(en)] building blocks are connected into a chain by bridging NH2 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.