Octaureasamarium(III) triiodide

Abstract

The Sm atom of the title compound, [Sm(CH4N2O)8]I3, is eight‐coordinate, with eight monodentate urea ligands bound through their O atoms; the corresponding polyhedron is a distorted double‐capped trigonal prism. All the urea mol­ecules are involved in intramolecular hydrogen bonds. This compound is a rare example of a lanthanide complex containing no water and in which the anions do not serve as ligands.

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

“…However, a greater variety of compositions is observed for the compounds of lanthanide bromides: the complexes can contain four carbamide molecules and four water molecules or six carbamide molecules and two water molecules, namely, [Ln(Ur) 4 4 ]Br 3 , which can be due to spatial char acteristics of the central atom. In this case, the coordi nation number of the rare earth metal atom does not change and remains equal to 8 and the coordination polyhedron is a tetragonal antiprism with a higher or lower degree of distortion.…”

“…We have earlier studied the complexes of erbium and lutetium bromides with carbamide [Ln(Ur) 4 (H 2 O) 4 ]Br 3 and [Ln(Ur) 6 (H 2 O) 2 ]Br 3 (Ln = Er and Lu) [5]. The coordination of the ligands in these compounds was found to occur through the oxy gen atoms of the water and carbamide molecules.…”

“…Lanthanum bromide forms two dif ferent crystalline compounds, whose compositions correspond to the molar ratio of the starting reactants in the syntheses of [La(Ur) 4 …”

“…The crystalline com plexes of lanthanide iodides LnI 3 ⋅ 4Ur ⋅ 4H 2 O (Ln = La, Nd, Eu, Gd, Dy, Ho, Er, Y) preparatively obtained at room temperature [3] are characterized by the com plex cations [Ln(Ur) 4 (H 2 O) 4 ] 3+ in the structure, and there is no coordination of the iodide ions by the lan thanide atoms. Anhydrous compound SmI 3 ⋅ 8Ur [4] was also synthesized at room temperature, and its structure contains the octa(carbamide)samarium complex cations and uncoordinated out of sphere iodide ions.We have earlier studied the complexes of erbium and lutetium bromides with carbamide [Ln(Ur) 4 (H 2 O) 4 ]Br 3 and [Ln(Ur) 6 (H 2 O) 2 ]Br 3 (Ln = Er and Lu) [5]. The coordination of the ligands in these compounds was found to occur through the oxy gen atoms of the water and carbamide molecules.…”

“…The crystalline com plexes of lanthanide iodides LnI 3 ⋅ 4Ur ⋅ 4H 2 O (Ln = La, Nd, Eu, Gd, Dy, Ho, Er, Y) preparatively obtained at room temperature [3] are characterized by the com plex cations [Ln(Ur) 4 (H 2 O) 4 ] 3+ in the structure, and there is no coordination of the iodide ions by the lan thanide atoms. Anhydrous compound SmI 3 ⋅ 8Ur [4] was also synthesized at room temperature, and its structure contains the octa(carbamide)samarium complex cations and uncoordinated out of sphere iodide ions.…”