Interactions of the Rh24+ formamidinate complex Rh2(μ-form)2(μ-O2CCF3)2(H2O)2 (form=N, N′-di-p-tolylformamidinate anion)with nucleobases and nucleosides

The Rh2 4+ formamidinate complex Rh2(μ-form)2(μ-O2CCF3)2(H2O)2 (form =N, N′-di-p-tolylformamidinate anion) reacts with adenine and N6,N6-dimethyladenine in molar ratio 1:1 and 1:2 giving mono- and bis-axial adducts Rh2(μ-form)2(μ-O2CCF3)2(L)n (L = adenine, N6,N6-dimethyladenine; n = 1, 2) with the adenine ligands coordinated through the N(3) atoms. In contrast when both the N(3) and N(9) atoms are blocked, the complex reacts in a different way. Adenosine (ado) in fact coordinates through the dimetal core leading to the Rh2 5+ complex Rh2(μ- form)2(O2CCF3)(μ-ado)2 which has been characterized by EPR spectroscopy. In this complex adenosine behaves as a bidentate mono-anionic ligand coordinated at the equatorial positions through N(1) and the deprotonated amino nitrogen. Similarly the complex Rh2(μ-form)2(μ-O2CCF3)2(H2O)2 reacts with cytosine, 1-methylcytosine and cytidine via a mono-electron oxidation leading to the paramagnetic complexes Rh2(μ-form)2(O2CCF3)(μ-L)2 (L = cytosine, 1-methylcytosine, cytidine) with the cytidinic ligands equatorially coordinated through N(3) and the deprotonated amino nitrogen atoms.