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 [Re3Mo3Q8(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 {Re3Mo3Q8}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 M6 cluster core. Reaction of [Re3Mo3Q8(CN)6]n– (Q = S, n = 6; Q = Se, n = 5) complexes with the 4‐tert‐butylpyridine (TBP) leads to compete substitution of coordinated cyano ligands and formation of two new heterometallic complexes [Re3Mo3Q8(TBP)6] (Q = S, Se) obtained with high yields. DFT calculations show a large distortion of the M6 metal cores in the complexes.