Reactions of the iridathiabenzene complex Cp*Ir(2,5-dimethylthiophene) with Co-2(CO)(8), Co-4(CO)(12), and (eta(6)-C(6)H(3)Me(3))Co-4(CO)(9)

With the goal of preparing an eta(6)-iridathiabenzene complex of CO4(CO)(12), the ring-opened iridathiabenzene complex Cp*Ir(C,S-2,5-Me(2)T) (1), where 2,5-Me(2)T is 2,5-dimethylthiophene, was reacted with Co-4(CO)(12), Co-2(CO)(8), and (eta(6)-C(6)H(3)Me(3))Co-4(CO)(9). Only in the reaction of (eta(6)-C(6)H(3)Me(3))CO4(CO)(9) under mild conditions (35-40 degrees C) was the eta(6)-iridathiabenzene cluster [eta(6)-Cp*Ir(C,S-2,5-Me(2)T)] Co-4(CO)(9) (7) obtained. At higher temperatures, the reaction yielded Cp*Ir(eta(4)2,5-Me(2)T . Co-4(CO)(11)) (6), in which the 2,5-Me(2)T ligand is coordinated through its diene to the Ir and through its sulfur to a Co of the cluster. Reactions of Co-4(CO)(12) and Co-2(CO)(8) with 1 yielded Cp*Ir(eta(4)-2,5-Me(2)T . Co-4(CO)(11)) (2), an isomer of 6, which converts to the desulfurized linear tetranuclear cluster [Cp*Ir(C(Me)=CHCH-C(Me))(mu-CO)(2)Co](2) (3); this species contains bridging iridacyclopentadiene units. Cluster 3 has a structure with a Co-2(mu-CO)(2) core and Cp*Ir(C(Me)=CHCH=C(Me))(CO) (4) end groups. In fact, 3 can be prepared from Co-2(CO)(8) and 4. Molecular structures of 2-4 are reported, together with a discussion of pathways that lead to their formation.