Sr₄Ga₃Mo₂₆O₄₈ Containing Mo₇ Clusters and Infinite Mo₇-Mo₁₀-Mo₇ Chains

The crystal structure of the stronium gallium molybdate Sr₄Ga₃Mo₂₆O₄₈ is characterized by quasi-isolated monocapped octahedral Mo₇ clusters and infinite Mo chains arranged in layers parallel to the ac plane of the monoclinic unit cell. The repeat unit of the chains is the tricluster Mo₂₄ chain fragment consisting of one Mo₁₀ and two Mo₇ clusters. The Mo-Mo distances range between 2.584 (1) and 2.786 (1) Å in the Mo₇ clusters and between 2.5963 (9) and 2.938 (1) Å in the chains. The shortest Mo-Mo distance between Mo₇ clusters is 3.1575 (9) Å and between Mo₇ clusters and the chains 3.171 (1) Å, which excludes any direct Mo-Mo interactions. The Mo-O distances range from 1.922 (6) to 2.163 (6) Å, as usually observed in reduced Mo oxides. The four crystallographically independent Sr²⁺ ions have coordination numbers of 11 or 12 with an environment in each case based upon a distorted cubo-octahedron. The Sr-O distances range from 2.495 (6) to 3.105 (5) Å. The Ga³⁺ ions are approximately tetrahedrally or octahedrally coordinated by oxygen atoms. The Ga-O distances vary between 1.902 (6) and 2.059 (6) Å for the octahedral sites, and between 1.830 (5) and 1.873 (6) Å for the tetrahedral site.

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