CRYSTAL-STRUCTURE OF TH3B2C3

The crystal structure of Th3B2C3 has been determined by single crystal X-ray analysis. The lattice parameters of the monoclinic cell (first setting) are: a = 3.703 (2) A ̊, b = 9.146 (4) A ̊, c = 3.773 (1) A ̊ and γ = 100.06 (7)°; space group: P2/m (C 1 2h), Z = 1. Intensity measurements were obtained from a fourcircle diffractometer. The structure was solved by Patterson methods and refined by full matrix least squares calculation. For an asymmetric set of 401 independent reflexions the final R-value is 0.079. The structure contains octahedra, tetrahedra and trigonal prisms of Th-atoms. The trigonal prisms are centered by boron atoms, Th-octahedra by carbon atoms Cl; Carbon atoms C2 actually have octahedral coordination 5 Th + 1 B. The structural chemistry of Th3B2C3 with respect to the crystal structures of ThC and ThBC is discussed. © 1979.