Studies on pentakisantipyrine copper(II) perchlorate

Abstract

Five coordinated antipyrine (A) complex of copper(II) perchlorate, [CuA₅](ClO₄)₂ has been prepared. Both the electric conductivity and the cryoscopic determination of molecular weight in nitrobenzene solution show that the complex dissociates into three ions. Differential thermal analysis gives one peak at about 285°C owing to the explosion of the complex. Infrared spectrum reveals the presence of both strongly and weakly coordinated antipyrine molecules in the complex. The complex in 1,2-dichloroethane absorbs at 16130 (ε=51) cm 15630 (ε=53) and 14500 (ε=56) cm¹. These d-d transitions with comparatively high intensities suggest C_4v symmetry for the complex ion [CuA₅]²⁺. A square pyramidal structure with four antipyrine molecules in the square plane at normal Cu-O bond distance and one antipyrine occupying the axial position with an elongated Cu-O bond, is assigned to the complex ion.