Synthesis and crystal structure of cobalt(II) and copper(II) complexes of 3,3′-biisoxazolidines as chelating ligands

New mononuclear Cu(II) and Co(II) complexes [Cu{L-1}(NO3)(2)]center dot H2O (1) and [Co{L-2}(H2O)(3))](NO3)(2) (2), with conformationally flexible isoxazolidine ligands, namely 3,3'-bi{2-methyl-5-phenyl}isoxazolidine (L-1) and 3,3'-bi{2-methyl-5-pyridyl}isoxazolidine (L-2), were synthesized and characterized. X-ray crystallographical analysis reveals that the Cu(II) atoms adopt a distorted octahedral environment. The ligand L-1 forms five-membered chelates via the isoxazolidine nitrogen atoms. The Co(II) atom in 2 is in a distorted octahedral geometry. The ligand L-2 coordinates the metal center with formation of two chelate rings, involving donors of two isoxazolidine and pyridyl groups. In the complex cation, three donor atoms of the ligand occupy the MN3 facial positions.