This report describes studies on the mobility of metal-metal bonds within the frameworks of unsymmetrical Ru4S4 clusters. A low-symmetry derivative of (MeC(5)H(4))(4)RU(4)S(4) (1) was prepared by methylation with MeO(3)-SCF3 (MeOTf) to give [MeC(5)H(4))(4)RU(4)S(3)(SMe)](+) (1Me(+)). Crystallographic characterization of [1Me]OTf revealed a distorted tetrahedron of Ru atoms with two Ru-Ru bonds and four Ru-Ru nonbonding contacts. The M-M and M-S distances demonstrate that the cluster geometry is little affected by methylation, as shown by the similarity of the cores in 1 and 1Me(+). For example the Ru-S(Me) distances are only ca. 0.05 Angstrom shorter than other comparable Ru-S contacts in the cluster. H-1 NMR studies indicate that the crystallographically determined structure is retained in solution; i.e., there are three types of(MeC(5)H(4))Ru sites in a 1:2:1 ratio. At higher temperatures, line broadening of two of the CH3C5H4 signals is observed, indicative of chemical exchange between (MeC(5)H(4))Ru sites. Magnetization transfer experiments confirm chemical exchange between the major and one of the two minor (MeC(5)H(4))Ru sites. This process requires the movement of both Ru-Ru bonds, Cyclic voltammetry shows that 1Me(+) undergoes a 2 e oxidation at 480 mV vs 1(2+/0). Studies using differential pulse voltammetry indicate that the Delta E(1/2) separating the 1Me(2+10) redox events is similar to 10 mV. Oxidation of 1Me(+) with 2 equiv of (C5H5)(2)FePF6 gave green-colored salts of 1Me(3+). The high-temperature H-1 NMR spectra of 1Me(3+) indicate a 3:1 ratio of Ru sites consistent with time-averaged C-3 upsilon symmetry while the low-temperature spectrum indicates that the (MeC(5)H(4))-Ru sites are nonequivalent.