Silver(I) and silver(III) complexes of biguanides and N′-amidinoisoureas

Abstract

The preparation and characterization of some quadricovalent cationic complexes of silver(I) and silver(III) with biguanides and N′-amidinoisoureas have been described. Silver(I) complexes were characterized by elemental analysis, conductance measurements, IR and UV spectral studies and thermal analysis. These complexes are colourless and may be classified into 4 main types: [AgLA 2], [AgL′A 2|X, [AgL″ 2]X and [Ag′A 2]X L= N′-amidinoisourea, L′ = biguanide, N-alkylbiguanide or O-alkyl N′-amidinoisourea, L″ = n-propylbiguanide, A = N 2O or NH 3, X = SO 4 2 , NO 3, OH or HSO 4. Silver(III) complexes are all brown-red to orange-red and may be represented by formulae [AgL 2]X and [AgL′ 2]X 3 = N′=amidinoisourea, L′ = biguadine or O-alkyl N′-amidinoisourea, X = SO 4 2 or OH. These complexes were characterized by elemental analysis, oxidimetric titrations, magnetic susceptibility measurements and IR spectral studies. Thermal analysis indicate the dimeric nature of some silver(I) complexes. Silver(I) and silver(III) complexes are suggested to have tetrahedral and square planar configuration, respectively. IR spectra indicate the presence of stronger metal-ligand bonding in silver(III)_complexes.