Metallo-guanines and metallo-guanosines

Metallo-guanines of the type M(G)₂·2H₂O] M = Ni^II, Fe^II, Cu^II and UO₂ ^II; G = anionic guanine], M(G)₂(GH)· H₂O] (M = Co^II and Mn^II; GH = neutral guanine), Pd(G)₂]·2H₂O and Zn(G)Cl]₂ have been isolated and characterised. Anionic guanine functions as a bidentate ligand and links through N(3) and N(9). E.p.r. data indicate that the Cu^II complex has a highly distorted octahedral structure. The magnetic susceptibility data suggest that the Co^II and Ni^II complexes possess pseudooctahedral geometry. Neutral guanines are probably unidentate and coordinate either through N(3) or N(9). The isolated guanosine complexes are of the types: M(Gs)₂·H₂O] M = Ni^II and Cu^II, Gs = anionic guanosine] Pd(Gs)₂]·2H₂O and UO₂(Gs)₂]. I.r. data indicate that guanosine also functions as a bidentate ligand, but coordinates through N(1) and C₂ — NH₂. The electronic absorption spectra of the complexes indicate that guanine is a stronger ligand than guanosine.