Structure determination of a new apatite: Ba5OsO5)3Cl

The crystal structure of Ba5(OsO5)3Cl is described. Ba5(OsO5)3Cl, MT = 1395.3, hexagonal, P63cm, a = 10.928(2) Å, c = 7.824(5) Å, V = 809.2(6) Å3, Dx =6.290 Mg/m3. λ(MoKα) = 0.71069Å, F(000) = 1170, room temperature, final R = 0.051 for 2900 observed reflections. The structure is isomorphous with Ba5(ReO5)3Cl and is similar to that of standard chlorapatite; the PO4 tetrahedra are replaced by pyramidal OsO5 groups.