A complete family of isostructural cluster compounds with cubane-like M(3)S(4)M' cores (M = Mo,W; M' = Ni,Pd, Pt): comparative crystallography and electrochemistry

By reaction of the geometrically incomplete cubane-like clusters (eta(5)-Cp')(3)Mo(3)S(4))]pts] and (eta(5)-Cp')(3)W(3)S(4)]pts] (Cp' = methylcyclopentadienyl; pts = p-toluenesulfonate) with group 10 alkene complexes, three new heterobimetallic clusters with cubane-like cluster cores were isolated: (eta(5)-Cp')(3)W(3)S(4)M'(PPh(3))]pts] (5]pts], M' = Pd; 6]pts], M' = Pt); (eta(5)-Cp')(3)Mo(3)S(4)Ni(AsPh(3))]pts] (7]pts]). The compounds 5]pts]-7]pts] are completing the extensive series of clusters (eta(5)-Cp')(3)M(3)S(4)M'(EPh(3))]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 (eta(5)-Cp')(3)M(3)S(4)M'(EPh(3))]pts] due to distinctly different cell parameters, which in the molecular structure of 5](+) is reflected in a slightly different orientation of the PPh(3) 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.