Binding sites between palladium(II) and nucleosides or nucleotides and crystal structure of [Pd(diethylenetriamine)(guanosine)](ClO4)2

Abstract

The interactions between [Pd(dien)Cl]Cl and some nucleosides and nucleotides were studied by nmr. The binding site of guanosine, guanosinemonophosphoric acid, xanthosine, and inosine is N(7). Cytidine is coordinated to palladium through N(3). Adenosinemonophosphate acts as a bidentate, binding two different palladium atoms at N(1) and N(7).The crystal structure of [Pd(dien)(guanosine)](ClO4)2 has been determined by X-ray diffraction. The crystals are orthorhombic, space group P212121, with a = 13.422, b = 14.587, c = 12.432, and Z = 4. The structure was refined by block-diagonal least-squares analysis to a conventional R factor of 0.047 and a weighted Rw = 0.043. The coordination around the palladium atom is square planar. Guanosine is bonded to palladium through N(7). The planar purine ring makes an angle of 63.4° with the palladium coordination plane. The structure is stabilized by hydrogen bonding.