Ionic acetamide coordination in its complexes with rare-earth iodides

Abstract

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.

Keywords:

• Acetamide
• Rare-earth metals
• Complexes
• Iodides
• Ionic type of coordination