Spectral and structural studies of mono- and binuclear copper(II) complexes of salicylaldehyde N(4)-substituted thiosemicarbazones

Abstract

Three copper(II) complexes of salicylaldehyde N(4)-phenyl thiosemicarbazone (H 2L 1) and two copper(II) complexes of N(4)-cyclohexyl thiosemicarbazone (H 2L 2) have been synthesized and characterized by different physicochemical techniques like magnetic studies and electronic, infrared and EPR spectral studies. The complexes [ ( CuL 1 ) 2 ] · 1 2 H 2 O ( 1 ) and [(CuL 2) 2] ( 4) having dimeric structure. The thiosemicarbazones bind to the metal as dianionic ONS donor ligand in all the complexes, except in the complex [Cu(HL 1) 2] · H 2O ( 2). In complex 2, the ligand moieties are coordinated as monoanionic (HL −) ones. Two of the complexes [CuL 1dmbipy] · H 2O ( 3) and [CuL 2dmbipy] ( 5) have been found to possess the stoichiometry [CuLB], where B = 4,4′-dimethyl-2,2′-bipyridine (dmbipy). The coordination geometry around copper(II) in 5 is trigonal bipyramidal distorted square based pyramidal (TBDSBP), as obtained by X-ray diffraction studies.