Structure of Barbituratobis(2,2'-Dipyridyl)copper(II) Heptahydrate

Abstract

The structure of the complex [Cu(Bipy)₂(BA)] ∙ 7H₂O (I), where Bipy is 2,2'-dipyridyl, and BA^2– is the barbituric acid anion (H₂BA), is determined (CIF file CCDC no. 1887338). The thermal decomposition and IR spectrum of complex I are studied. The crystals are orthorhombic: a = 26.118(3), b = 27.685(3), c = 15.683(2) Å, V = 11 370(2) ų, space group Fdd2, Z = 16. The discrete structure of the polar crystal consists of neutral [Cu(Bipy)₂(BA)] particles and molecules of crystallisation water . The Cu²⁺ ion is bound to the N atoms of two bidentate Bipy molecules and the N atom of the BA²⁻ ion at the vertices of the trigonal bipyramid CuN₅. Compound I is the first example of the metal complex only with the N-coordinated anions of barbituric acid (BA²⁻, НBA⁻). The structure is stabilized by hydrogen bonds O−H∙∙∙O and N−H∙∙∙O to form a three-dimensional network with the π–π interaction between the Bipy molecules. The compound begins to lose water at ~50°С and is completely dehydrated above 200°С.