Complexes of yttrium, lanthanum, and erbium halides with carbamide: Syntheses and structures

Abstract

New complexes of yttrium and lanthanum bromides and erbium chloride with carbamide (Ur), [Y(Ur)4(H2O)4]Br3 (I) and [La(Ur)4(H2O)4]Br3 (II), [La(Ur)6(H2O)2]Br3 (III), and [Er(Ur)6Cl]Cl2 (IV), are synthesized and studied by X-ray diffraction analysis. In structures I–III, the coordination of the ligands (water and carbamide) by the metal occurs through the oxygen atoms. The coordination polyhedron of the rare-earth metal atoms is a distorted square antiprism (coordination number 8), and the bromide ions are not included into the internal coordination sphere of the complexes. In compound IV, the internal coordination sphere of the complex includes six carbamide molecules and one chloride ion, and the coordination polyhedron of Er is a distorted pentagonal bipyramid (coordination number 7). Specific features of the structures of the crystalline carbamide derivatives of chlorides, bromides, and iodides of the considered rare-earth metals are compared. A distortion of the planar structure of some carbamide ligands, depending on their number in the complex cation and on the nature of the complex, is observed.