Abstract

M. Srinivas Mohan, K. Radha, Y. Laxmi Kumari, K. B.Santhi Sudha and P. Jhansi laxm

The acid dissociation constants and the binary formation constants for the mono(ML) and bis binary complexes (ML2) formed by the interaction of Ni(II) and Cd(II) with Phosphonoformic acid –PFA(L) were determined at 37.0 0 C and μ = 0.15mol.dm-3 (KNO3). The formation and stability of mixed ligand complexes (MLA) containing PFA, Ni(II) or Cd(II) and a second ligand (A) = 2,2’- Bipyridyl, 1,10-phenanthroline, Dipyridyl amine, Ethylene diamine, Oxalic acid, Malonic acid were studied. The stability of the mixed ligand complexes and the corresponding binary complexes were quantitatively compared in terms of the parameters Dlog K. The influence of the nature of the two ligands L and A on the stability of the mixed ligand complexes are discussed and pH metal species distribution profiles for some selected systems are graphically represented. The configurations possible for the Ni(II) and Cd(II) complexes were evaluated using the semi-empirical and the density functional theory calculations respectively. PM 3 , a semi-empirical self-consistent method, was employed to obtain the 3D – geometries and relative energies of the possible isomers of Ni(II) complexes. The most stable structure among the possible ones is adjudged as the most probable structure. The antiviral activity of PFA is attributed to its ability to form stable binary and mixed ligand complexes.

Binary; mixed ligand; Phosnoformic acid; antiviral agent

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