Heavy-Metal-Nucleoside Interactions. 13. Synthesis and Spectroscopic Study of Organomercury Derivatives of Guanosine and Thymidine

Complexes of the stoichiometry RHg(GuoH-1), [RHg(Guo)]N03, and [(RHg)2GUOH-1]NO3 have been synthesized by reaction of the nucleoside guanosine (Guo) and RHg(II) in water (R = Me) or aqueous ethanol (R = Ph). Comparison of infrared spectra of the solid complexes and 1H nuclear magnetic resonance spectra of the complexes in dimethyl-d6 sulfoxide with spectra of Guo, [GuoH]N03, and Na[GuoH-1].H20 allows assignment of structures for these ambidentate ligand complexes. Deprotonation of N1 of Guo leads to coordination of RHg(II) at N1 in RHg(GuoH-1) and to both N1 and N7 in [(RHg)2GuoH-l]N03. The complexes [RHg(Guo)]N03 have RHg(II) bonded at N7 of the guanine base. Phenylmercuric hydroxide reacts with thymidine (dThd) in aqueous ethanol to form PhHg(dThdH-1).H20 with PhHg(II) bonded to N3 after deprotonation of dThd. Structures deduced for these solid complexes are in agreement with those suggested in earlier ultraviolet and Raman studies of the interaction of nucleosides and nucleotides with MeHg(II) in aqueous solution. The uses and limitations of vibrational spectra in assigning structures to such metal nucleoside complexes are outlined.