Steric influence of the 6-methyl group on the molecular and crystal structures of copper(II) chloride complexes with 2-(N-acetylamino)-6-methylpyridine

Abstract New coordination compounds of copper(II) chloride with 2-(N-acetylamino)-6-methylpyridine (L) of the compositions [Cu 2 L 2 Cl 4 ] ( 1 ), [CuL(H 2 O)Cl 2 ]·L ( 1a ), and [CuL 2 Cl][CuLCl 3 ]·C 2 H 5 OH ( 2 ) have been prepared by the reactions between ethanol solutions of L and ethanol solutions of CuCl 2 ·2H 2 O at different Cu:L ratios. The compounds have been characterized by a set of methods including elemental analysis, IR-spectroscopy, single-crystal X-ray diffraction analysis, and magnetic susceptibility measurements in the range 5–300 K (for 1 ). The crystal structures of 1 and 1a revealed distorted square-pyramidal geometry around Cu(II) centers, while in 2 both distorted square-pyramidal and trigonal–bipyramidal coordinations are present. L acts as a bidentate chelate ligand bound to the metal center through the pyridine N atom and the acetyl O atom. The results of the study demonstrate that the presence of 6-methyl substituent in L provides a high steric hindrance, precluding the formation of complexes with a distorted octahedral coordination of Cu(II).