Octahedral rhenium cluster chemistry: from high-temperature syntheses to the elaboration of new inorganic/molecular hybrid compounds via solution route

Ternary Re-Y-X and quaternary M-Re-Y-X systems (Y = chalcogen, X = halogen) with rhenium in low oxidation state are extremely rich in compounds based on the octahedral Re-6 metal core (`cluster') enclosed in a (pseudo)cube of eight so-called `inner' ligands L-i and an octahedron of six additional `apical' ligands L-a, giving anionic units of the general formula [(Re6L8L6a)-L-i](n-). These compounds are synthesized by solid-state chemistry route and are characterized by a wide variety of inter-unit linkages via various types of bridges or are built from isolated anionic units with intrinsic molecular character. The solubility of the latter in polar solvents allows new research approaches. Thus they can act as precursors for coordination chemistry and can be manipulated as molecular bricks, assembled with various counter-cations, non accessible by direct synthesis, and/or functionalized with unusual partners.