A novel type of tetradentate uracil derivative in a dodecahedral eight-coordinate chelate complex: catena-bis(.mu.-6-amino-3-methyl-5-nitrosouracilato-N5,O4,N1,O2)cadmium(II)

Abstract

The crystal structure of the complex catena-bis(~-6-amino-3-methyl-5-nitrosouraciIato-~,~,N',~)cadmium(II) has been determined. It crystallizes in the tetragonal space group P41212-0: with cell dimensions a = b = 7.885 (0) A, c = 26.359 (2) A, V = 1638.8 ( I ) A', and Z = 4. The structure was solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R = 0.018 for 1956 data. The structure consists of a sequence of complex polymeric sheets, linked by hydrogen bonds. Each ligand is coordinated to two different cadmium atoms, and each cadmium atom is coordinated by four pyrimidine ligands. These ligands are equivalent with one cadmium atom binding through N5 and 0 4 atoms, while the other cadmium atom binds through the N1 and 0 2 sites. The cadmium atom is eight-coordinated and shows a C, symmetry that can be described as a dodecahedron with the mmmm arrangement of ligands. The A vertices are all occupied by oxygen atoms and the B vertices by nitrogen atoms.