Magnetic and spectroscopic studies of structure and bonding in hexafluorophosphate and hexafluoroarsenate complexes of copper(II)

Abstract

Complexes of composition CuL4(EF6)2 (where L is pyridine, 3-methylpyridine, or 4-methylpyridine and E is P or As) have been prepared and characterized by epr, electronic and infrared spectroscopic, and magnetic susceptibility studies. Results are consistent with elongated tetragonal–octahedral structures with coordinated anions. The coordinating strength of PF6− is estimated to be less than that of AsF6− and both are considered weaker than perchlorate. Analysis of the epr data indicates significant metal to heterocyclic ligand π-electron delocalization, the extent and nature of which depends on the orientation of the heterocyclic ring in the CuL4 chromophore. Analysis of infrared data suggests that the intensities of the v1 and v2 vibrations as they occur in EF6− complexes generally provide an indication of the strength of metal–anion interactions.