1,2-Bis-[(5-methyl/chloro/nitro)-2-1H-benzimidazolyl]-1,2-ethanediols and their PdCl2 complexes

1,2-Bis-[(5-methyl)-2-1H-benzimidazolyl]- (L-1), 1,2-bis-[(5-chloro)-2-1H-b enzimidazolyl]- (L-2), 1,2-bis-[(5-nitro)-2-1H-benzimidazolyl]-1,2-ethanedi ol (L-3) and their PdCl2 complexes were synthesized and characterized by el emental analysis, molar conductivity, i.r. and H-1-n.m.r. spectra. The benz ene ring substituents lead to a decrease in melting point. The methyl group reduces the solubility and the acidity of L-1 and Pd(L-1)Cl-2, whereas the Cl and NO2 groups increase the solubility and the acidity of L-2, L-3, Pd( L-2)Cl-2 and Pd(L-3)Cl-2. In Pd(L-1)Cl-2 and Pd(L-2)Cl-2 complexes, the lig ands act as a bidentate through two nitrogen atoms. In Pd(L-3)Cl-2, ligand coordination occurs through one OH group oxygen atom and one of the benzimi dazole nitrogen atoms.