Cubane-Type [Mo 3 S 4 M] Clusters with First-Row Groups 4-10 Transition-Metal Halides Supported by C 5 Me 5 Ligands on Molybdenum

A synthetic protocol was developed for a series of cubane-type [Mo S M] clusters that incorporate halides of first-row transition metals (M) from Groups 4-10. This protocol is based on the anionic cluster platform [Cp* Mo S ] ([1] ; Cp*=η -C Me ), which crystallizes when K(18-crown-6) is used as the counter cation. Treatment of in situ-generated [1] with such transition-metal halides led to the formation of [Mo S M] clusters, in which the M/halide ratio gradually changes from 1:2 to 1:1.5 and to 1:1, when moving from early to late transition metals. This trend suggests a tendency for early transition metals to tolerate higher oxidation states and adopt larger ionic radii relative to late transition metals. The properties of the [Mo S Fe] cluster 6 a were investigated in detail by using Fe Mössbauer spectroscopy and computational methods.