Insertion of alkynes into the heterocycle of (η5-pentaalkyl-2,3-dihydro-1,3-diborolyl)(η5-pentamethylcyclopentadienyl)ruthenium: Formation and characterization of 4-borataborepine ruthenium complexes

Regio-specific insertion of alkynes into the folded heterocycle of decamethyl-1,3-diboraruthenocene (2) leads to 4-borataborepine complexes 4. Steric crowding of R2 causes elimination of the distant B-R1 moiety with formation of boratabenzene complexes 5.