A complete family of isostructural cluster compounds with cubane-like M3S4M′ cores (M = Mo, W; M′ = Ni, Pd, Pt): Comparative crystallography and electrochemistry

By reaction of the geometrically incomplete cubane-like clusters [(η5-Cp′)3Mo3S4)][pts] and [(η5-Cp′)3W3S4][pts] (Cp′ = methylcyclopentadienyl; pts = p-toluenesulfonate) with group 10 alkene complexes, three new heterobimetallic clusters with cubane-like cluster cores were isolated: [(η5-Cp′)3W3S4 M′(PPh3)][pts] ([5][pts], M′ = Pd; [6][pts], M′ = Pt); [(η5-Cp′)3Mo3 S4Ni(AsPh3)][pts] ([7][pts]). The compounds [5][pts]-[7][pts] are completing the extensive series of clusters [(η5-Cp′)3M3 S4M′(EPh3)][pts] (M = Mo, W; M′ = Ni, Pd, Pt; E = P, As) which allows the consequences of replacing a single type of atom on structural and NMR and UV/vis spectroscopic as well as electrochemical properties to be determined. Single-crystal X-ray structure determinations of [5][pts]-[7][pts] revealed that [5][pts] was not isomorphous to the other members of the series [(η5-Cp′)3M3 S4M′(EPh3)][pts] due to distinctly different cell parameters, which in the molecular structure of [5]+ is reflected in a slightly different orientation of the PPh3 ligand. Electrochemical measurements on the series showed that the Mo-based clusters were more difficult to oxidize than their W-based analogues. The Pd-containing clusters underwent two-electron oxidation processes, whereas the Ni- and Pt-containing clusters underwent two separated one-electron oxidation processes.