ChemInform Abstract: Synthesis, Crystal Structure, and Physical Properties of a New Boride Ga2Ni21B20with a Modified Zn2Ni21B20-Type Structure

A ternary boride Ga 2 Ni 21 B 20 , with modified Zn 2 Ni 21 B 20 -type structure (space group I 4/ mmm , and lattice parameters a = 7.2164(1) A, c = 14.2715(4) A), was synthesized from the constituent elements. Single crystal diffraction data reveal Ni at 8 f site splitting into 16 m position with nearly half occupancy. In this structure, [Ni 6 B 20 ] cages share ligand boron atoms with [Ga 2 B 4 Ni 9 ] hexa-capped square prisms, forming two dimensional layers. Layers are interconnected via Ga−Ni interactions and build up a three-dimensional framework. Quasi-two-dimensional infinite planar nets formed by intercrossed Ni atoms are embedded. Ga 2 Ni 21 B 20 is a metallic Pauli paramagnet, in agreement with electronic structure calculations, resulting in 8.2 states eV −1 f.u −1 at the Fermi level.