Crystal structure and chemical bonding analysis of BaPtCd₂

The new ternary intermetallic phase, BaPtCd₂, was synthesized by solid-state reaction from direct combination of the elements in a stoichiometric mixture. The reaction was done at 850 C for 15 h, followed by an equilibration at 600 C for 4 d. The crystal structure was determined by X-ray diffraction method on a single crystal. BaPtCd₂ is isotypic to MgCuAl₂ and crystallizes in the orthorhombic space group Cmcm [a = 4.467(2), b = 11.143(4), c = 8.240(3) Aa, V = 410.2(3) Aa³, and Z = 4]. Barium atoms are linked together forming zigzag chains. Cadmium atoms are bonded to each other forming six-membered rings of platinum centered boat and anti-boat conformations. BaPtCd₂ contains 16 electrons per formula unit and belongs to the electron poorest compounds with MgCuAl₂ type structure. Calculations based on the linear muffin-tin orbitals method in the atomic spheres approximation show that significant bonding states in BaPtCd₂ are unoccupied. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)