Transition-metal variation as a probe into the catalytic activity of metallaboranes

The reactivity of two isoelectronic and isostructural metallaboranes, nido-[(Cp*Rh)2B6H10], 1 and nido-[(Cp*Ru)2B6H12], 2 with alkynes demonstrates that a change in metal from group 9 to group 8 creates difference in the reactivity pattern. Compound 1 catalyzes the cyclotrimerization of a variety of internal and terminal alkynes to yield 1,3,5- and 1,2,4-substituted benzene. In contrast, compound 2 shows no reactivity toward alkynes. A set of alkynes have been verified with nido-1 that yielded several benzene derivatives in satisfactory yields.