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

Copper phosphates, [Cu(dtbp)2(pzet)2]·H2O (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 CH2CH2OH 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.