Lanthanum Gallium Bismuthide, LaGaBi2

The ternary rare-earth gallium bismuthide LaGaBig has been prepared through reaction of the elements. Its structure (Pearson symbol h7P24, hexagonal, space group P6/mmm, Z= 6, a = 13.5483(4) A, c = 4.3937(1) A) contains columns of Lae trigonal prisms centered by Bi atoms. These columns are surrounded by a framework consisting of three-atom-wide Bi ribbons and Gae rings. Additional Bi atoms are sandwiched between pairs of Ga6 rings. LaGaBbi is structurally closely related to Lai3Ga8Sb2i. A retrotheoretical analysis of the structure through extended Huckel band structure calculations suggests an interesting electronic situation in which strong multiple bonding in the Ga-Ga network coexists with weak hypervalent bonding in the Bi-Bi network and confirms the metallic behavior seen in electrical resistivity measurements.