Chemistry of Diruthenium Analogue of Pentaborane(9) With Heterocumulenes: Toward Novel Trimetallic Cubane-Type Clusters

Reactions of the CS2 and CO2 heterocumulene ligands with nidoruthenaborane cluster [1,2-(Cp*Ru)(2)(mu-H)(2)B-3-H-7), 1, were explored (Cp* = pentamethylcyclopentadienyl). Compound 1 when treated with CS2 underwent metal-assisted hydroboration to yield arachno-ruthenaborane [(Cp*Ru)(2)(B3H8)-(CS2H)], 2, with a dithioformato ligand attached to it. The chemistry of 2 was then explored with various transition metal carbonyl compounds under photolytic and thermolytic conditions. Thermolysis of 2 with [Mn-2(CO)(10)] resulted in the formation of an unprecedented cubane-type cluster [(Cp*Ru)(2)Mn-(CO)(3)(CS2H2)B3H4], 3, with a rare [M3E5] formulation (E = B, S). On the other hand, when compound 2 was photolyzed in the presence of [Mn-2(CO)(10)], it yielded an incomplete cubane-type cluster [(Cp*Ru)(2)Mn(CO)(3)BH2(CS2H2)], 4. The room-temperature reaction of 2 with [Fe-2(CO)(9)] yielded heterometallic arachno clusters [(Cp*Ru)(CO)(2){Fe(CO)(3)}(2)S2CH3], 6 and [(Cp*Ru)(2)(B3H8)-(CO){Fe(CO)(3)}(2)(CS2H)], 7. In contrast, photolysis of 2 with [Fe-2(CO)(9)] yielded a tetrahedral cluster [(Cp*Ru)(CO)(2)S(mu-H){Fe(CO)(3)}(3)], 8, tethered to an exo-polyhedral moiety [(Cp*Ru)(CO)(2)]. Compound 6 provides an unusual bonding pattern by means of fusing the wing-tip vertex (S) of the [Fe2S2] butterfly core by an exo-polyhedral [(Cp*Ru)(CO)(2)] unit. Density functional theory calculations were carried out to provide insight into the mechanistic pathway, electronic structure, and bonding properties.