Mixed ligand complexes of platinum (II) with histidine as primary ligand and punnes, pyrimidines and nuc1eosides as secondary ligands

Abstract

Mixed ligand complexes of Pt(II) with histidine as the primary ligand and nucleic acid constituents-adenine, guanine, cytosine, uracil, adenosine, guanosine, inosine, cytidine and uridine as secondary ligands have been synthesized and characterized. The complex-<em>cis</em>-[Pt(HisH)-CI₂].H₂O (<b>1</b>) (HisH = histidine) has been prepared and reacted in basic solution with purines, pyrimidines or nucleosides in a 1:1 moral ratio to form mixed ligand complexes. In all these complexes histidine acts as a bidentate ligand coordinating to Pt(II)through the imidazole ring nitrogen (N₃) and the amino group. The secondary ligand adenine, adenosine or inosine coordinates to the Pt(II) ion through ring nitrogen (N₇). In pyrimidines and corresponding nucleoside complexes coordination to platinum (II) is through ring nitrogen (N₃) In the guanine and guanosine mixed ligand complexes of Pt(II), these ligandsbind to the metal ion in a bidentate manner through N₇ and C₆O^- forming a five-membered chelate ring. In all these complexes carboxylic group of bidentate histidine is free.