This work describes the physico-chemical studies of metal complexes with N and S donor ligands. Emphasis has been given to the synthesis and characterization of polyazamacrocycles and dithiocarbamato complexes of transition metal ions and Sn(IV). They have been characterized by FT-IR, NMR (1H, 13C and 119Sn), mass spectrometry and X-ray crystallography. The synthesis of 14-membered hexaaza macrocyclic complexes of the type [CuL]X2, [CuL1]X2, [CuL(N3)(ClO4).3/2O]n, [CuL(N3)2] and [CuL1(N3)(ClO4)]n was reported. The effect of anions on the gross geometry and chemical properties of the Cu(II) ion have been studied. The crystal structure of [Ni(L)][CoCl4] clearly establishes the cationic-anionic interaction. Rare C?H---Ni anagostic interactions, generally exhibited by d8 complexes also observed. The interaction of potassium bis(2,2-dithiopiperazinato-2,2-diaminodiethylamine (K2L) with R2SnCl2 leading to the formation of bimetallic complexes of the type R4Sn2L2 have been reported. The synthesis of a mononuclear precursor complex, [(CH3)2Sn(tpdtc)] and several heterobimetallic derivatives of the type, [(CH3)2Sn(tpdtc)]MCl2 have also been reported.