The crystal structures of CusZn8, CusCds and FeaZna0 have been studied using single-crystal X-ray diffraction techniques. All three alloys have the body-centred cubic space group 1743m with four formula units per unit cell. Lattice parameters are 8.878 (4), 9.615 (10) and 9.018 (3) A respectively for CusZn8, CusCd8 and the pseudocell of FeaZn~0. Evidence shows a new superstructure of 36 A at the composition FeaZn~0. Values of lattice parameter as a function of composition are given for the CusCd8 phase. New data are presented on the three structures, and the ordering of the alomic species is compared with that reported by previous workers. Significant differences in our ordering for FeaZn~0 are attributed to our different composition within the 7 phase. X-ray diffraction intensity data were collected using a 3-circle automatic single-crystal diffractometer and Mo Ke X-radiation. The crystal structures were refined using full-matrix least-squares methods to final R values of 6.1%, 7-5 %, and 5.5 % respectively. A discussion of possible reinterpretations for these and other ~, brass structures is presented.

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The structure was determined with Cu-K, diffractometer data by Patterson and full-matrix least-squares methods, the final R being 0.078 for 366 independent reflexions. The molecule has 4 symmetry, with mean dimensions Sn-C = 2.14, C-C = 1.41 8, C-Sn-C = 109.5". B.C., CanadaPRELIMINARY X-ray structure analysis of Ph,Ge*CO*Ph, as part of an investigation of the structures of a-silyl and a-germyl ketones,l*2 showed the crystals to be tetragonal, space group P42,c, with 2 = 2. This implies apparent molecular symmetry I , which probably results from a disordered arrangement of molecules in the crystal. The crystal structure appears to be similar to the structures of the compounds Ph4M (M = C, Si, Ge, Sn, or Pb) which have been investigated: 394 however detailed structural information is available only for tetraphenylmethane.5 We now describe the structure of tetraphen ylt in.

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