Apical Cyanide Ligand Substitution in Heterometallic Clusters [Re3Mo3Q8(CN)6]n- (Q = S, Se)

A number of transition metal cluster compounds can be obtained only in the melt of inorganic cyanides and, therefore, contain terminal cyanide ligands. Substitution of these ligands, which is often necessary to change the physicochemical properties of the clusters, is an urgent problem because of their low reactivity in substitution reactions. In this work, a synthetic approach has been developed for the substitution of CN-ligands in the heterometallic cluster anions [Re(3)Mo(3)Q(8)(CN)(6)](n-) (Q = S, n = 6; Q = Se, n = 5) by the 4-tert-butylpyridine (TBP) molecules. Two new compounds, namely [Re3Mo3S8(TBP)(6)] (1) and [Re3Mo3Se8(TBP)(6)] (2), were obtained with high yields and crystallized under solvothermal conditions. It has been shown that compounds 1 and 2 are based on the paramagnetic cluster cores {Re(3)Mo(3)Q(8)}(0) containing 23 cluster valence electrons (CVE). The geometry of the new compounds has been investigated using X-ray structural analysis. The electronic structure has been analyzed using the DFT calculations showing large distortion of M-6 cluster core.