Tetrakis(2,2′-bi­pyridine)­tetra-μ₃-hydro­xo-di-μ-tri­fluoro­acetato-tetracobalt(II) diiodide diaceto­nitrile monohydrate: a compound containing a tetranuclear `cubane'-type cobalt(II) core

A new compound, [Co₄(C₂F₃O₂)₂(OH)₄(C₁₀H₈N₂)₄]I₂·2C₂H₃N·H₂O, containing a tetranuclear cobalt(II)–hydroxo core with a cube-like structural geometry is reported. The four Co^II coordination polyhedra are irregular octahedra and the Co^II atoms are linked by three hydro­xo and tri­fluoro­acetate ions resulting in a Co₄O₄ core with approximate tetrahedral symmetry. The coordination polyhedra share edges with short Co⋯Co distances. A bond valence analysis shows that a cube-like arrangement of atoms in a tetranuclear cluster is ideal for the clusters [M₄(OR)₄]⁴⁺ (R is a strongly binding group) and [M₄O₄]⁸⁺ when the metal ions are in oxidation states of +2 and +4, respectively.