The structure of onoratoite, Sb8O11X2Sb8O11X2 (X=ClX=Cl, Br) revisited

The crystal structure of Sb8O11Cl2 (onoratoite) is redetermined in the triclinic space group P-1. The crystal structure was previously described by a partially disordered model in the monoclinic space group C2/mC2/m containing some partially occupied oxygen atoms. The new structural model features exclusively atomic positions that are fully occupied. The crystal structure was solved from single crystal data and the unit cell parameters are a=10.317(2) Åa=10.317(2) Å, b=11.269(2) Åb=11.269(2) Å, c=13.939(3) Åc=13.939(3) Å, α=79.29(2)°α=79.29(2)°, β=76.29(2)°β=76.29(2)°, γ=73.00(2)°γ=73.00(2)°, Z=2Z=2, R=0.0637R=0.0637. It contains antimony oxide in the form of infinite tubes interleaved with halide ions, a main feature very similar to the previous model. However, in the new model the tubes contain both [SbO4E] (E = 5s2 lone pair of electrons) trigonal bipyramids and [SbO3E] tetrahedral, whereas the old model was composed entirely of trigonal bipyramidal [SbO4E] units. The isostructural compound Sb8O11Br2 was synthesized as well.

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