ABSTRACT.A new hydrazide Shiff base ligand GHL1 (5-bromo-2-hydroxybezylidene)-3,4,5-trihydroxybenzohydrazide) was prepared by refluxing of trihydroxybenzhydrazide with an ethanolic of 5-bromo-2-hydroxybenzaldehyde. The ligand reacted with Ni(II), Cu(II), Zn(II) and Cd(II) (acetate salts). All the complexes were characterized by elemental analysis, molar conductivity, TGA, UV-Vis and FT-IR spectral studies. All the complexes have octahedral geometry except Ni(II) complex which has tetrahedral geometry.

Four tridentate ONS ligands, namely 2-hydroxyacetophenonethiosemicarbazone (H 2 L 1 ), the 2-hydroxyacetophenone Schiff base of S-methyldithiocarbazate (H 2 L 2 ), the 2-hydroxy-5-nitrobenzaldehyde Schiff base of S-methyldithiocarbazate (H 2 L 3 ), and the 2-hydroxy-5-nitrobenzaldehyde Schiff base of S-benzyldithiocarbazate (H 2 L 4 ), and their complexes of general formula [Ni(HL 1 ) 2 ], [ML] (M = Ni II or Cu II ; L = L 1 , L 2 , L 3 and L 4 ), [Co(HL)(L); L = L 1 , L 2 , L 3 and L 4 ] and [ML(B)] (M = Ni II or Cu II ; L = L 2 and L 4 ; B = py, PPh 3 ) have been prepared and characterized by physico-chemical techniques. Spectroscopic evidence indicates that the Schiff bases behave as ONS tridentate chelating agents. X-ray crystallographic structure determination of [NiL 2 (PPh 3 )] and [CuL 4 (py)] indicates that these complexes have an approximately square-planar structure with the Schiff bases acting as dinegatively charged ONS tridentate ligands coordinating via the phenoxide oxygen, azomethine nitrogen and thiolate sulfur atoms. The electrochemical properties of the complexes have been studied by cyclic voltammetry.

Aseries of new complexes of the type [MLCl 2 ] where M=Mn (II),Co(II),Ni(II),Cu(II),Zn(II),Cd(II) L=L 1 or L 2 represents di-Schiff base ligands: {L 1 =(N,N'E,N,N'E)-N,N'-(phenanthrene-9,10-diylidene) bis (benzene-1,2-diamine). L 2 =(N,N'E,N,N'E)-N,N'-(phenanthrene-9,10-di ylidene)bis(benzene-1,3-diamine)} have been prepared in (1:1)(M:L) molar ratio and charactrerized by electrical conductivity,magnetic moment, IR , UV-VIS and metal content analysis. Synthesis and Characterization of Mn(II) ,Co(II) ,Ni(II) ,Cu(II) …. 94 Conductivity data in DMF and DMSO solution showed that all complexes are non-electrolytes. Magnetic moment and electronic spectra indicate that some of the complexes have a tetrahedral geometry and the others have an square planar environment. The antibacterial activity against E.coli and S.aureus of L 1 and L 2 and some of their complexes derived from Cu(II) and Zn(II) illustrates that the complexes have higher activity than the corresponding organic ligand.