Copper phosphates and phosphinates with pyridine/pyrazole alcohol co-ligands: Synthesis and structure

Abstract

Copper phosphates, [Cu(dtbp)(2)(pzet)(2)]center dot H(2)O (1) and [Cu(dtbp)(2)(pyme)(2)] (2), as well as copper phosphinate, [Cu(dppi)(2)(pyet)(2)] (3) have been synthesized by the reaction of copper acetate with di-tert-butyl phosphate (dtbp) or diphenyl phosphinate (dppi) in the presence of pyridine base having hydroxyl group, namely, 3,5-dimethylpyrazole-2-ethanol (pzet) or 2-(hydroxymethyl) pyridine (pyme) or 2-(2-hydroxyethyl) pyridine (pyet). Single crystal X-ray diffraction studies reveal that copper ion in all the three complexes is bonded to two phosphoryl ions (P(O)O ) and two pyridine co-ligands. The crystal structure of 1 reveals that the hydroxyl group of the CH(2)CH(2)OH moiety of pzet ligand exhibits a positional disorder between the non-bonding position and the bonding position with respect to the central copper ion along the Jahn-Teller axis. Hence, the structure of 1 can be considered to exhibit both 'square-planar' and 'octahedral' coordination geometries simultaneously for the copper ion in the same complex. A similar situation for the -OH groups has not been observed in the complexes 2 and 3 and hence the coordination geometry around the copper ion is axially elongated octahedron. (C) 2011 Elsevier B.V. All rights reserved.