Acetylcarbamide complexes of some lanthanide bromides and chlorides: Syntheses and structures

Syntheses, IR spectroscopy, and X-ray diffraction analyses were carried out for acetylcarbamide (AcUr) and new complexes La(AcUr)(2)(H2O)(5)]Br-3 (I), [Pr(AcUr)(2)(H2O)(5)]Br-3 (II), [Nd(AcUr)(2)(H2O)(5)]Cl-3 (III), and [Sm(AcUr)(2)(H2O)(5)]Cl-3 (IV) (CIF files CCDC 992841 (AcUr), 992842 (I), 992844 (II), 992843 (III), and 992845 (IV)). The crystals of compounds I-IV contain complex cations [Ln(AcUr)(2)(H2O)(5)](3+) (coordination number of lanthanum is 9) and uncoordinated halide ions. The coordination polyhedron in the cases of compounds I and IV is a one-capped tetragonal antiprism, and it is a three-capped trigonal prism in the cases of compounds II and III. Molecules AcUr are coordinated to the Ln atoms via the bidentate mode through the oxygen atoms. They are transformed from the initial cis-trans conformation to the trans-trans conformation, which is due to the rotation of the -C(O)-NH2 fragment around the nitrogen atom of the imino group. The angles between the O(1)C(1)N(3) and O(2)C(4)N(3) planes in the coordinated AcUr molecules are different, which can be due to the electronic structure of the central atom and spatial characteristics of the complexes. The coordinated AcUr molecules are joined to the halide ions and water molecules of the adjacent complex cations by hydrogen bonds.