Structure and Bonding of La2NiBi: Structure and Bonding of La2NiBi

La2NiBi was synthesized by heating a cold pressed pellet of the elements in a sealed and evacuated silica tube at 1070 K. The structure was determined via powder and single crystal X-ray diffraction. La2NiBi crystallizes orthorhombically, in the space group Pnma: a = 838.88(6), b = 455.61(11), c = 1210.4(2) pm and V = 0.46261(14) nm(3) (wR = 0.1002, 1001 F-2 values, 26 variables, Z = 4). La2NiBi represents a higher congener of La2NiSb and adopts a ternary ordered version of the Bi3Ni structure type. Similar to La2NiSb, the nickel atoms form infinite zigzag chains (259 pm Ni-Ni) with trigonal-prismatic lanthanum coordination. One rectangular face of the lanthanum prism is capped by a bismuth atom (333.08-364.74 pm La-Bi, 281.18 pm Ni-Bi). These zigzag chains run along the b axis. DFT based band structure calculations and DOS representations suggest metallic behavior. This was confirmed via temperature dependent impedance spectroscopic measurements. A Seebeck coefficient of -10 VK-1 in the temperature range up to 873 K substantiates this finding. Thermal analyses show that the compound is stable up to 873 K under inert gas conditions and degrades at higher temperatures. The magnetic measurements show almost no grain boundary nickel impurities characterizing La2NiBi as a weak Pauli paramagnet.