Metal-Rich Phosphides Obtained from the Lead Flux: Synthesis, Crystal, and Electronic Structure of Sr 5 Pt 12 P 9 and BaPt 3 P 2

Using a high-temperature ampoule technique and lead metal as a flux, we have grown single crystals and determined crystal structures from single-crystal X-ray diffraction data of two metal-rich phosphides, Sr Pt P ( / , = 6.1472(3) Å, = 25.1713(13) Å, = 6.4635(3) Å, β = 99.604(2)°, = 2, = 0.0326, = 0.0786) and BaPt P ( , = 6.3605(6) Å, = 6.8541(7) Å, = 11.3493(12) Å, = 4, = 0.0231, = 0.0501). Both compounds belong to their own structure types and feature 3D networks of Pt and P atoms, with the channels occupied by alkaline earth metal cations. Density functional theory calculations reveal Sr Pt P to be a metal, while BaPt P is a narrow-gap semiconductor with a band gap of 0.24 eV. Bonding analysis shows that both compounds feature networks of prominent covalent localized Pt-P bonds, responsible for their structural stability, as well as additional weaker and, likely, less localized Pt-Pt interactions.