Synthesis, Crystal Structure, and Chemical Bonding of Ba 2 SiP 4

Ba 2 SiP 4 was synthesized by heating of the elements at 1173 K and the crystal structure was determined from single‐crystal X‐ray diffraction [ I 4 2 d, a = 990.57(3) pm, c = 731.80(3) pm; Z = 4]. The novel structure is homeotypic to hp‐Zn 2 SiO 4 but the SiP 4 tetrahedra are exclusively bridged by P–P bonds [ d (P–P) = 222 pm] which is hitherto unprecedented. The three‐dimensional SiP 4 network is analogous to β‐cristobalite if oxygen is formally replaced by a P–P dimer. Barium fills the voids and is coordinated by eight phosphorus atoms. DFT calculations indicate covalent Si–P and P–P bonding and an indirect energy gap of ca. 1 eV.