A cluster with a mixed M6X12/M6X8 environment: The La6Cl11Co structure

The title compound was synthesized from La, LaCl3 and Co under Ar atmosphere at 800 °C. It crystallizes in space group P42/n (no. 86) with lattice constants a=11.308(2) Å and c=14.441(3) Å. The structure features an isolated Co-centered La6 octahedron with all corners and edges, and 2 of its 8 triangular faces coordinated by Cl atoms. The La6Co octahedron is significantly distorted, and the La coordination by Cl atoms deviates from the common close-packing arrangements found in other reduced rare earth metal halides. Structure, bonding and physical properties of the compound have been investigated.