Adenosine adducts with first row transition metal perchlorates

Abstract

Adducts of adenosine (ado) with 3d metal perchlorates were synthesized by refluxing mixtures of ligand and salt in ethanol-triethyl orthoformate. Metal(III) perchlorates formed adducts involving 2:3 metal to ado molar ratio (MCr, Fe), i.e., M2(ado) 3(ClO 4) 6·4H 2O, whereas 1:1 adducts were produced by metal(II) perchlorates, as follows: M(ado)(ClO 4) 2·2H 20 (MMn, Co, Ni, Cu); and M(ado)(Cl0 4) 2 (MFe, Zn). All the new complexes seem to be polymeric, involving a linear chainlike backbone with single ado bridges between adjacent metal ions in most cases, i.e., −(-M-ado-)- n. The coordination sphere of each metal ion is completed by terminal aqua, ado and, with the exception of the Cu 2+ complex, −OClO 3 ligands, in the case of the hydrated new complexes. Ado would be binding through the N(1) and N(7) ring nitrogens, when functioning as bridging, bidentate. As regards the two water-free M(II) complexes (MFe, Zn), which are apparently distorted tetrahedral, the evidence available is interpreted in terms of the presence of tridentate bridging ado, binding through N(1), N(7) in the same fashion as above, and through one of the ribose hydroxyl oxygens, which form weaker bonds to M 2+ ions located in a neighboring linear polymeric −(-M-ado-)- n unit; the coordination sphere in these complexes is completed by one −OClO 3 ligand.