Synthesis, characterization, and crystal structures of iodides and polyiodides of scandium complexes with urea and acetamide

Abstract

Iodides and polyiodides of scandium complexes containing urea (Ur) and acetamide (AA) have been synthesized and characterized by elemental analysis, IR spectroscopy, and X-ray diffraction. The trigonal crystals of [Sc(L)6]I3 (L = Ur, AA) and monoclinic crystals of [Sc(Ur)6][I3]3 are isomorphous to the earlier reported [M(Ur)6]I3 (M = Ti, V, Cr, Fe) and [Ln(Ur)6][I3]3 (Ln = Yb, Lu), respectively. Therefore, scandium in its complexes with urea and iodine links rows of 3d transition elements and rare-earth elements; it continues the tendency of formation of polyiodides with different structures from isomorphous iodides, which was found for other metal(III) urea complexes. In the orthorhombic crystals of [Sc(AA)6][I5][I3]I, the first example of the M(III) acetamide polyiodide, metal ions in complex cations are located at the centers of distorted octahedral arrangements of oxygen atoms of acetamide; iodide ions are not coordinated. The crystals of [Sc(AA)6][I5][I3]I contain V-shaped pentaiodide, linear triiodide, and isolated iodide anions.