Inorganic Chemistry, Vol.42, No.15, 4585-4596, 2003
Cubane-type heterometallic sulfido clusters: Incorporation of two metal fragments into a dinuclear ReS(mu-S)(2)ReS core affording bimetallic M2Re2(mu(3)-S)(4) clusters (M = Ru, Pt, Cu) or trimetallic MM' Re-2(mu(3)-S)(4) clusters via incomplete cubane-type MRe2(mu(3)-S)(mu(2)-S)(3) intermediates (M = Ru, Rh, Ir; M' = Mo, W, Pd, Ru, Rh)
Reactions of a dirhenium tetra(sulfido) complex [PPh4](2)[ReS(L)(mu-S)(2)ReS(L)] (L = S2C2(SiMe3)(2)) with a series of group 8-11 metal complexes in MeCN at room temperature afforded either the cubane-type clusters [M-2(ReL)(2)-(mu(3)-S)(4)] (M = Cp*Ru (2), PtMe3, Cu(PPh3) (4); Cp* = eta(5)-C5Me5) or the incomplete cubane-type clusters [M(ReL)(2)-(mu(3).S)(mu(2).S)(3)] (M = (eta(6)-C6HMe5)Ru (5), Cp*Rh (6), Cp*Ir (7)), depending on the nature of the metal complexes added. It has also been disclosed that the latter incomplete cubane-type clusters can serve as the good precursors to the trimetallic cubane-type clusters still poorly precedented. Thus, treatment of 5-7 with a range of metal complexes in THIF at room temperature resulted in the formation of novel trimetallic cubane-type clusters, including the neutral clusters [{(eta(6)-C6HMe5)Ru}{W(CO)(3)}(ReL)(2)(mu(3)-S)(4)], [(CP*M){W(CO)(3)}(ReL)(2)(mu(3)-S)(4)] (M = Rh, Ir), [(Cp*Ir){Mo-(CO)(3)}(ReL)(2)(mu(3)-S)(4)], [{(eta(6)-C6HMe5)Ru}{Pd(PPh3)}(ReL)(2)(mu(3)-S)(4)], and [(Cp*Ir){Pd(PPh3)}(ReL)(2)(mu(3)-S)(4)] (13) along with the cationic clusters [(Cp*Ir)(Cp*Ru)(ReL)(2)(mu(3)-S)(4)][PF6] (14) and [(Cp*Ir){Rh(cod)}(ReL)(2)(mu(3)-S)(4)][PF6] (cod = 1,5-cyclooctadiene). The X-ray analyses have been carried out for 2, 4, 7, 13, and the SbF6 analogue of 14 (14') to confirm their bimetallic cubane-type, bimetallic incomplete cubane-type, or trimetallic cubane-type structures. Fluxional behavior of the incomplete cubane-type and trimetallic cubane-type clusters in solutions has been demonstrated by the variable-temperature H-1 NMR studies, which is ascribable to both the metal-metal bond migration in the cluster cores and the pseudorotation of the dithiolene ligand bonded to the square pyramidal Re centers, where the temperatures at which these processes proceed have been found to depend upon the nature of the metal centers included in the cluster cores.