Hydrogen Activation by Benzene-Ruthenium Complexes in Aqueous Solution: Synthesis, Molecular Structure, and Intercalation of the Cluster Cation [{C₆H₆)₄Ru₄H₄]²⁺

Abstract

The hydrogenation of the aqua complex [(C₆H₆)Ru(H₂O)₃]²⁺, prepared in situ by hydrolysis of (C₆H₆)₂Ru₂Cl₄ in water, was found to lead to the tetranuclear cluster dication [(C₆H₆)₄Ru₄H₄]²⁺ (1) which crystallizes as the dichloride from the aqueous solution. In the presence of acetate ions, however, the reaction yields the dinuclear cations [(C₆H₆)₂Ru₂H(OOCCH₃)X]₊ (X=OH: 2, X=Cl: 3) which crystallize as the hexafluorophosphate salts. The X-ray crystal-structure analysis of [(C₆H₆)₄Ru₄H₄]Cl₂ reveals the cluster dication 1 to consist of a tetrahedral ruthenium framework; the four hydrido ligands are presumably coordinated to three faces and to one edge of the Ru₄ tetrahedron. The cationic complexes 1 and 2 have been found to intercalate in sodium hectorite.