CaPt4P6, first calcium-containing representative of the ternary pyrite-derived pnictides of the BaPt4As6 type: Synthesis, crystal, and electronic structure

Journal of Solid State Chemistry. 2023. Vol. 322. Article 123969.

Makhaneva A. Y., Zakharova E., Nesterenko S., Konstantin A. Lyssenko, Kuznetsov A.

Mixed calcium-platinum phosphide CaPt4P6 was synthesized using flux-assisted high-temperature ampoule
technique. According to single-crystal XRD data it crystallizes in the monoclinic space group C2/c with Z ¼ 4 (a ¼
8.1361(3) Å, b ¼ 7.9489(3) Å, c ¼ 11.3803(5) Å, β ¼ 90.860(2)o, R1 ¼ 0.0240, wR2 ¼ 0.0618) and belongs to the
BaPt4As6 structure type, the structure of which is derived from pyrite structure where one atom of alkaline earth
metal per formula unit occupies P2-unit position. DFT calculations predict all known representatives of the
BaPt4As6 structure type to be narrow-gap semiconductors (calculated bandgap values are: 0.43 eV (CaPt4P6), 0.57
eV (SrPt4P6), 0.27 eV (SrPt4As6) and 0.40 eV (BaPt4As6)). Bonding analysis establishes that all these compounds
are based on the 3D framework of the Pt-Pn and Pn-Pn interactions, with AE cations occupying the voids with
varying degree of the distortion of the AE coordination.

Keywords: DFT, crystal structure, chemical bonding, Platinum-rich compounds, Phosphides, Flux-assisted crystal growth