Syntesis and Crystal Structure of Cs2Nb6Br5F12: A Nb6 Cluster Compound with a One-Dimensional Nb6Br5F7F6 Unit Connection

The synthesis and the crystal structure of Cs₂Nb₆Br₅F₁₂ containing octahedral niobium clusters are presented in this work. This bromofluoride is based on a Nb₆Lⁱ₁₂F^a₆ (L=Br and F) unit and crystallizes in the orthorhombic system (space group, Cccm; Z=4; a=9.2446(2) Å, b=13.6256(3) Å, and c=17.1665(4) Å; R=0.0241). Fluorine and bromine are randomly distributed on the inner ligand positions, Lⁱ, that edge-bridge the Nb₆ cluster whereas fluorine fully occupies the apical positions (L^a). The units are linked to each other by apical ligands leading to an original one-dimensional unit connection. The cesium atoms are statistically distributed on several sites that describe parallel channels along the 1 0 0] direction. The influence of fluorine ligands upon the stabilization of this structure type as well as the structural relationships with Ba₂Zr₆Cl₁₇(B), Nb₆F₁₅, and NaMo₆Cl₁₃ will be evidenced and discussed.