SPECTRAL AND STRUCTURAL STUDIES OF METAL-COMPLEXES OF 1-PHENYLGLYOXALBIS(N(3)-DIETHYLTHIOSEMICARBAZONE)

Nickel(II), copper(II) and palladium(II) complexes of 1-phenylglyoxal; bis{N(3)-diethylthiosemicarbazone}, H(2)Pg4DE, have been prepared, st udied spectroscopically and their crystal structures solved. H(2)Pg4DE and the three complexes have been characterized by IR, electronic, H- 1 NMR (Ni, Pd) and ESR (Cu) spectra. Upon formation of these complexes , loss of the N(2)H hydrogens from both thiosemicarbazone moieties occ urs, and the ligands coordinate to. the metal centers as dianionic, te tradentate N2S2 ligands. The nickel(II) and copper(II) complexes, [M(P g4DE)], coordinate in the expected 5-5-5-chelate ring system, but [Pd( Pg4DE)] coordinates with 5-6-4-membered chelate rings. The thiosemicar bazone moiety attached to the phenyl keto carbon in [Pd(Pg4DE)] forms the 4-membered chelate ring coordinating via N(2) rather than the azom ethine nitrogen, N(1). (C) 1998 Elsevier Science Ltd. All rights reser ved.