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‘)₃W₃S₄M‘(PPh₃)][pts] ([5][pts], M‘ = Pd; [6][pts], M‘ = Pt); [(η⁵-Cp‘)₃Mo₃S₄Ni(AsPh₃)][pts] ([7][pts]). The compounds [5][pts]−[7][pts] are completing the extensive series of clusters [(η⁵-Cp‘)₃M₃S₄M‘(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‘)₃M₃S₄M‘(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.