Heteronuclear, mixed-nucleobase complexes. 2. (μ-1-Methyluracilato- N3, O4) (μ-1-methylcytosine- N3, O2)- cis-diammineplatinum-(II)·silver dinitrate·silver nitrate·2.5 water

Abstract

The preparation and crystal structure of a mixed 1-methyluracilato, 1-methylcytosine complex of composition cis-[(NH 3) 2Pt(C 5H 5N 2O 2)(C 5H 7N 3O)Ag(OH 2)](NO 3) 2·AgNO 3·2.5H 2O is described. The compound crystallizes in the triclinic system, space group P 1 , with a=7.421(1), b=12.784(2), c= 14.355(2) Å, α=108.89(2), β=92.45(2), γ= 105.22(1)°, Z=1. The structure was refined to R= 0.050 and R w= 0.046 with use of 4327 independent reflections. Binding of the cis-(NH 3) 2Pt II moiety is through N3 of the uracil and N3 of the cytosine ring. One silver is directly coordinated to O4 of uracil and O2 of cytosine, leading to a PtAg separation of 2.906(1) Å. Pairs of dinuclear Pt, Ag units are linked via aqua ligands and bridging nitrate ions to two additional silver ions which, in turn, complete their coordination spheres by an aqua ligand and a monodentate nitrate each. As a result, large 12-membered rings, consisting of four Ag ions, two H 2O groups, as well as two ONO bridges are formed. AgAg distances in these rings vary between 3.553(1) and 6.898(1) Å.