Core conversion reactions of the cubane-type metal-sulfido clusters: shape shift, contraction, and expansion of the MM'Re2S4 Cubanes (M = Ir, Rh, Ru; M' = Pt, Pd)

Treatment of incomplete cubane-type clusters [(Cp*M){Re(L)}(2)(mu(3)-S)(mu(2)-S)(3)] (M = Ir (1a), Rh (1b); Cp* = eta(5)-C(5)Me(5); L = S(2)C(2)(SiMe(3))(2)) and [{(Pmb)Ru}{Re(L)}(2)(mu(3)-S)(mu(2)-S)(3)] (Pmb = eta(6)-C(6)Me(5)H) with 1 equiv of [Pt(PPh(3))(3)] gave tetranuclear tetra(sulfido) clusters having raft-type cores, [(Cp*M){Pt(PPh(3))(2)}{Re(L)}(2)(mu(3)-S)(4)] (M = Ir (3a), Rh) and [{(Pmb)Ru}{Pt(PPh(3))(2)}{Re(L)}(2)(mu(3)-S)(4)], which presents a sharp contrast to the reactions with [Pd(PPh(3))(4)] reported previously, affording the cubane-type clusters [(Cp*M){Pd(PPh(3))}{Re(L)}(2)(mu(3)-S)(4)] (M = Ir (2a), Rh) and [{(Pmb)Ru}{Pd(PPh(3))}{Re(L)}(2)(mu(3)-S)(4)]. The reactions of 2a with diphosphines P2 resulted in the conversion of its cubane-type core into the analogous raft-type frameworks, forming [(Cp*Ir){Pd(P2)}{Re(L)}(2)(mu(3)-S)(4)] (P2 = cis-Ph(2)PCH=CHPPh(2) (6), Ph(2)PCH(2)CH(2)PPh(2), Ph(2)PCH(2)CH(2)CH(2)PPh(2)). On the other hand, when 2 was allowed to react with Ph(2)PCH(2)PPh(2) (dppm) as P2, the trinuclear tri(sulfido) cluster [(Cp*Ir){Re(L)}(2)(mu(3)-S)(2)(mu(2)-S)(mu(2)-dppm)] (9a) was obtained. Alternatively, this cluster 9a and its Rh analogue 9b were derived from the incomplete cubane-type clusters 1a and 1b by treatment with dppm. It has also been found that further treatment of the cubane-type cluster 2a with excess [Pd(PPh(3))(4)] affords the heptanuclear tetra(sulfido) cluster [(Cp*Ir){Pd(PPh(3))}(4)Re(2)(mu(3)-L)(2)(mu(3)-S)(4)] (10). The detailed structures have been determined by the X-ray analyses for 3a, 6, 9a, and 10.