Treatment of sonicated calf thymus DNA with the antitumor active metallocene Cp2MoCl2 afforded a metallocene-DNA complex which was characterized by 31P NMR spectroscopy. In addition to the resonance for the phosphate backbone (δ −1.6), the spectrum contained 2 signals assigned to a phosphate bound Mo—DNA complex(es) (δ 37.2, 36.5) and a broad signal at δ 6.2 ppm. This result suggests that covalent attachment of the metallocene Cp2MoCl2 occurs via phosphate(O) coordination and is accompanied by local distortion of the DNA backbone. This result supports recent ICP studies with Cp2TiCl2 that have DNA detected DNA—metallocene adducts.
