The complexes of composition R 2 SiCl(SB) and R 2 Si(SB) 2 (R=CH 3 and C 6 H 5 and SB = anion of the Schiff base of sulphonamide and Ph 3 Si(SB) have been prepared by the reactions of Schiff base SBH with metal chlorides. The newly synthesized complexes have been characterized by elemental analysis, conductance measurements and molecular weight determinations. The mode of bonding and geometry of the complexes have been suggested on the basis of IR, UV and multinuclear 'H, l3 C and 29 Si NMR

more »

... tral studies. Schiff base and its silicon complexes have also been screened for their antibacterial activities, antifungal activities and nematicidal activities. The pathogenicity and virulence of certain microbial infections associated with ions of complexes have been found to be potent and broad-spectrum antibiotics. These results made it desirable to delineate a comparison between ligand and its silicon complexes. INTRODUCTION Organosilicon(IV) derivatives are known to be biologically active /1-4/ and exhibit interesting structural features /5-9/. Among these derivatives the triorganosilicon(IV) compounds with monofunctional bidentate ligands are of special interest, as in these derivatives silicon may be tetra-/5,6,9/ or penta-/1,5,8/ coordinated. The choice of the coordination number depends on the mono-or bidentate behaviour of ligands. The condensation products of sulpha drugs with aldehydes and ketones are biologically active and have good complexing ability too /10,11/. Sulpha drugs when administered in the form of metal complexes show increased biological activity /12-14/. Silicon is one element which possesses properties of both a metal and a nonmetal. This leads to a versatility in its chemical behaviour, so that silicon spreads itself throughout ionic, covalent, organometallic and colloidal chemistry and its derivatives find applications in such diverse fields as polymer chemistry, textile and paper industry, space exploration and even cosmetics. Sulpha drugs are a group of compounds used for eliminating a wide range of infections in human and other animal systems. The present paper deals with the striking structural features, synthesis and appreciable biological applications of the complexes of an important sulpha drug Schiff base. EXPERIMENTAL All the glass apparatus used during the experimental work was fitted with quick fit interchangeable standard ground joints. The glassware was first cleaned with chromic acid and water and then rinsed with acetone. These were then dried in an electric oven at 120°-125°C for few hours. The reactions were carried out under anhydrous conditions. During the course of the reactions, guard tubes packed with fused calcium chloride were used to protect the contents from moisture and melting points were determined in sealed capillary tubes. Synthesis of the Ligand (Fig.l) To obtain the ligand 2-acetylnaphthalene sulphaguanidine, 2-acetyl-naphthalene was mixed with sulphaguanidine in 1:1 molar ratio and retluxed on a water bath for five-six hours. Alcohol was used as the solvent. On cooling overnight in a refrigerator, crystals separated out which were further purified by washing with ethanol and finally recrystallized with acetone. The analyses and physical properties of the ligand are given in Table I . The unimolar and bimolar complexes were prepared by the reactions of triphenylchlorosilane, diphenyldichlorosilane, and dimethyldichlorosilane with the sodium salt of 2-acetylnaphthalene sulphaguanidine in dry methanol. The reaction mixture was refluxed for about 14-16 hours on a rotating head, during which the white precipitate of sodium chloride separated out. The contents were cooled and the precipitate of sodium chloride so formed was removed by filtration. Coloured solids were obtained on removal of the excess of the solvent and drying under reduced pressure for 3-4 hours. These were purified by repeated washing with a (1:1) mixture of dry methanol and cyclohexane, and their purity was checked by thin-layer chromatography (TLC) on silica gel.. The physical characteristics and analytical properties of the resulting isolated powdered solids are listed in Table I . The UV spectra of the silicon complexes were recorded in DMSO solution at room temperature.