Structure, twinning, and properties of Ce4Br3C4

The new compound Ce4Br3C4 can be prepared from Ce metal, CeBr3 and C (3:3:2 ) at 1020 degrees C. It crystallizes in P (1) over bar with a = 422.7(1)pm, b = 1103.4(3)pm, c = 1126.8(2) pm, alpha = 77.15(3)degrees, beta = 90.13(2 )degrees and gamma = 84.42(3)degrees. The crystals are characteristically t winned, the twin law being (1 0 0, 1/2 -1 0, 0 0 -1). The crystal structure contains puckered layers of edge sharing Ce6C2 octahedra. The mean C-C dis tance in the C-2 units is 133(5) pm. Ce4Br3C4 has at room temperature a spe cific resistivity of 100 m Omega cm and an effective magnetic moment of 2.5 5(3) mu(B) (Ce3+).