Oligomeric (eta(6)-arene) ruthenium(II) complexes of adenine and adenosine with N6,N7 coordination

Treatment of [{RuCl2(eta(6)-arene)}(2)] (arene=p-cymene, C6H6) with adenine (adeH), 9-ethyladenine (9etade) and adenosine (aden) provides the complexes [{Ru(ade) (eta(6)-p-cymene)}(4)](CF3SO3)(4) (2), [{Ru(9etadeH(-1)) (eta(6)-p-cymene)}(3)] (CF3SO3)(3) (3) and [{Ru(adenH(-1)) (mu(6)-C6H6)}(3)] (CF3SO3)(3) (4). The structures of complexes 2 and 3 were established by X-ray structural analysis. 2 crystallises in the tetragonal space group I4(1)/a with a=b=15.870(2), c=35.710(7) Angstrom, Z=4; 3 . 1.5H(2)O in the monoclinic space group C2/c with a=35.985(3), b=13.094(2), c=28.406(3) A, Z=8. Common to 2-4 is the participation of N6 and N7 in a five-membered chelate ring, which leads to a characteristic upheld shift in the H-1 NMR signal of the pyrimidine proton H2. The tetrameric complex 2 exhibits the mu-1 kappa N-9:2 kappa(2)N(6),N-7 coordination mode for the bridging adeninate ligands, the trimeric complexes 3 and 4 the mu-1 kappa N-1:2 kappa(2)N(6),N-7 mode for the 9-substituted derivatives.