Thermal, structural and electrical studies of the chloro complexes of cobalt, nickel and copper with 7,8-benzoquinoline

Abstract

The chloro compounds of 7,8-benzoquinoline with cobalt, nickel and copper were prepared in ethanolic solution from which solid compounds were isolated. The suggested structure for the cobalt compound is tetrahedral, whereas for the nickel and copper compounds it is polymeric octahedral. The techniques of thermogravimetry and differential thermal analysis show that the cobalt compound forms an intermediate compound before the metal oxide is formed. The nickel and copper compounds decompose with loss of organic ligand and chlorine to give the metal oxides. Electrical conductivities for the compounds at room temperature lie in the narrow range 3.09 × 10 −8 Ω −1 m −1 (for the copper compound) to 3.59 × 10 −7 Ω −1 m −1 (for the cobalt compound). The current-voltage characteristic for the uncomplexed 7,8-benzoquinoline is ohmic, but its complexes exhibit hysteresis. The temperature dependences of conductivity have been determined for the compounds and are used to measure the activation energies for conduction.