Coordination chemistry in the solid state: Cluster and condensed cluster-halides of the early transition metals

The "inner sphere" halides in M6X12 (edge-bridged) or M'gXg (face-capped) clusters are always augmented by six "outer sphere" halide (or other) ligands at the metal vertices. The inclusion of one of ca. 24 interstitials within M6X12 clusters of group 3 and 4 transition metals generates a large family of new cluster compounds that are stable in high temperature solid state systems. The electronic versatility provided by the centered interstitials greatly expands the variety of compositions, structures, and intercluster halogen-bridging modes. The condensation of metal clusters into a variety of infinite chain products, most of which are also centered, is also encountered.