The Phosphidosilicates SrSi 7 P 10 and BaSi 7 P 10

The new phosphidosilicates SrSi 7 P 10 and BaSi 7 P 10 were synthesized by solid‐state reactions, and their crystal structures determined by single‐crystal X‐ray diffraction [ P 1, Z = 1, SrSi 7 P 10 : a = 6.1521(1) Å, b = 8.0420(2) Å, c = 8.1374(2) Å, α = 106.854(1)°, β = 99.020(1)°, γ = 105.190(1)°; BaSi 7 P 10 : a = 6.1537(1) Å, b = 8.0423(2) Å, c = 8.1401(2) Å, α = 106.863(1)°, β = 99.050(1)°, γ = 105.188(1)°]. The compounds crystallize in a new triclinic structure type with vertex sharing SiP 4 tetrahedra, which assemble a non‐centrosymmetric diamond‐like network of T2 supertetrahedra. The alkaline earth cations reside in cuboctahedral voids. 31 P solid‐state MAS‐NMR spectra confirm the crystal structure. SrSi 7 P 10 and BaSi 7 P 10 exhibit the lowest charged SiP network in phosphidosilicates so far. Full‐potential DFT calculations classify both compounds as semiconductors with small indirect bandgaps of 1.1 eV.