Synthesis, structures and dielectric properties of two five-coordinate copper (II) complexes based on N-chloromethyl-1, 4-diazabicyclo[2.2.2]octane

The reaction of 1-(chloromethyl)-4-aza-1-azonia-bicyclo[2.2.2]octane chloride and divalent metal copper chloride in dilute hydrochloric acid and perchloric acid mediums yields two five-coordinate copper (II) complexes, C7H16Cl4CuN2O (1) with trigonal–bipyramidal geometry and C14H28Cl6CuN4O8 (2) with novel square–pyramidal geometry respectively. Their crystal structures have been determined by X-ray crystallography at room temperature and low temperature. Dielectric constants of these two complexes increase with increasing temperature and decrease with increasing frequency when measured at different temperatures and frequencies. The complex 2 is more sensitive to diverse frequencies than complex 1 and also shows dielectric anomaly and corresponding dielectric loss behavior at 173 K as the result of the disorder–order transition of perchlorate anions.