RbGa3S5 und CsGa3S5 – Zwei neue Strukturtypen

RbGa3S5 and CsGa3S5 – Two New Structure Types The title compounds RbGa3S5 and CsGa3S5 were synthesized by a solid state reaction starting from GaS, S and MN3 (M = Rb, Cs) as alkaline metal source. They crystallize in the space group P21/c with comparable lattice parameters but with completely different structures (RbGa3S5: a = 7,1530(6), b = 12,715(1), c = 10,1282(9) Å, β = 102,43(1)°, Z = 4; CsGa3S5: a = 10,6717(8), b = 12,763(1), c = 6,9265(6) Å, β = 91,168(9)°, Z = 4). In RbGa3S5 Rb together with S shows the topology of a hexagonal close packing in which Ga occupies 3/12 of the tetrahedral holes. The GaS4 tetrahedra are connected by common corners and edges forming a 3D‐network. The structure of CsGa3S5 is characterized by corrugated layers of edge‐ and corner‐sharing GaS4‐tetrahedra. Both compounds represent so far unknown structure types and thus two further structural alternatives for compounds with the composition MM3′Ch5.