Synthesis and characterization of complexes of trialkyl- and triarylphosphine gold(I) with thiolated purines and pyrimidines: a class of bifunctional compounds with potential antitumor activity

New complexes of the type R₃PAuL or (R₃PAu)₂(μ-L) where R=ethyl or phenyl and L=6-thioguanine, 2, 6- dithioxanthine, 2, 4-dithiouracil and/or dithioerythritol have been prepared. These complexes have been identified by using elemental analysis, ¹H, ¹³C and ³¹P NMR spectroscopy. The structures have been proposed based on these spectroscopic studies. Sulfur appears to be the binding site in disubstituted complexes of 2, 4-dithiouracil and 1, 4-dithioerythritol, while the phosphine gold(I) moieties appear to be S and N bonded in 2, 6-dithioxanthine and 6-thioguanine. The potential use of these complexes as antitumor drugs is discussed.