Denis V. Golubev

Structural features of the crystalline iodide complexes of some rare-earth elements with carbamide and acetamide

New acetamide and carbamide complexes LnI3 · 4Ur · 4H2O (Ln = La, Eu, Dy, Ho, Y; Ur is carbamide) and LnI3 · 4AA · 4H2O (Ln = Nd, Eu, Dy, Ho, Y; AA is acetamide) are synthesized. The complexes are characterized by the data of chemical analysis, IR spectroscopy, and X-ray diffraction analysis. The ligands (water, carbamide, and acetamide molecules) are coordinated by the rare-earth element atoms through the oxygen atom, and the coordination polyhedron is a distorted square antiprism. The iodide ions are not coordinated and are located in the external sphere. The structural characteristics of the complexes are compared in the series [Ln(L)4(H2O)4]I3 (Ln = La, Nd, Eu, Gd, Dy, Ho, Er; L = AA, Ur).

Complexes of gadolinium and erbium iodides with carbamide: Synthesis and structures

The novel carbamide complexes of gadolinium and erbium iodides of the composition LnI34Ur·4H2O (Ln = Gd, Er; Ur = carbamide) were synthesized and studied by X-ray diffraction and IR spectroscopy. The ligands are coordinated to the central Gd or Er atom through the O atoms of water or carbamide molecules. The coordination polylhedron of Ln atoms is a distorted square antiprism. The iodide ions are not coordinated and lie in the outer sphere.

Ionic acetamide coordination in its complexes with rare-earth iodides

A series of [Ln(CH3CONH2)4(H2O)4]I3 (Ln = rare-earth metal) complexes was completed with seven new compounds (Ln = Ce, Pr, Sm, Tb, Tm, Yb, Lu); two (Ln = Ce, Tm) were studied by X-ray diffraction. The coordination polyhedron of eight oxygen atoms is a distorted square antiprism. No tetrad effect was found for Ln–O bond lengths. The structure is stabilized by a system of intermolecular hydrogen bonds. The most striking feature of the structures is the recently predicted ionic acetamide coordination. The acetamide molecules are non-planar (the Ln–O–C–N torsion angles are 159–170°) and Ln–O–C bond angles vary in the 146.0–156.8° range.

Complexes of lanthanum, gadolinium, and erbium iodides with acetamide: Synthesis and structure

New acetamide complexes of lanthanum, gadolinium, and erbium iodides of the composition LnI3 · 4AA · 4H2 O (Ln = La, Gd, Er; AA = CH3CONH2) are synthesized and studied. The synthesized complexes are characterized by the data of chemical analysis and IR spectroscopy and are studied by X-ray diffraction analysis. The coordination of the ligands (water and acetamide molecules) by the lanthanum, gadolinium, or erbium atom occurs through the oxygen atoms. The coordination polyhedron of the Ln atom is a distorted square antiprism. The iodide ions are not coordinated and exist in the external sphere.

Synthesis and structural characterization of polyiodides of rare-earth urea complexes: crystal structures of [Ho(Ur)7][I3]3 and [Pr(Ur)8][I5][I3]2[I2]

Reactions of LnI3·nH2O, I2, and urea (Ur) produced rare-earth polyiodides [Ln(Ur)8][I5][I3]2[I2] (Ln = Pr, Nd, Sm–Tb) and [Ln(Ur)7][I3]3 (Ln = Ho, Er); the crystal structures of the praseodymium and holmium compounds were solved. In [Ho(Ur)7][I3]3, holmium ions are located at the centers of distorted pentagonal bipyramids (three independent complex cations) and an octahedra with a split vertex (one independent cation) of oxygens of coordinated urea. All triiodide anions are symmetric and linear; they are united in almost linear infinite chains by short contacts. The almost parallel chains of iodine atoms form infinite walls of honeycomb-like channels, and the columns of the complex cations are localized in these channels. Complex [Pr(Ur)8][I5][I3]2[I2] is isotructural to the earlier reported [Dy(Ur)8][I5][I3]2[I2]. Graphical abstract