Hypoxanthine, xanthine and theobromine complexes with palladium(II) and platinum(IV) chlorides

Abstract

Complexes of the general types Pd(L)(LH)Cl (LH=hxH, xnH, or tbH) and Pt(L)(LH)Cl3 (LH=hxH, or xnH) are formed by boiling under reflux 2∶1 molar mixtures of hypoxanthine (hxH), xanthine (xnH) or theobromine (tbH) and PdCl2 or PtCl4 in ethanol-triethyl orthoformate. These complexes appear to be linear chain polymeric species, characterized by single monoanionic L− ligands bridging between adjacent Pd2+ or Pt4+ ions. Inclusion of one terminal neutral LH and one terminal chloro-ligand completes the coordination sphere in the square-planar Pd2+ complexes, while the Pt4+ complexes aretrans-octahedral, involving three terminal chloro and one terminal LH ligand per platinum. The possible binding sites of the bidentate bridging L− and the unidentate terminal LH are discussed.