The first example of a transition metal (BB)-carboryne complex containing two boron atoms of the icosahedral cage connected to a single exohedral metal center (POBBOP)Ru(CO)(2) (POBBOP = 1,7-OP(i-Pr)(2)-2,6-dehydro-m-carborane) was synthesized by double B-H activation within the strained m-carboranyl pincer framework. Theoretical calculations revealed that the unique three-membered (BB) >Ru metalacycle is formed by two bent B Ru sigma-bonds with the concomitant increase of the bond order between the two metalated boron atoms. The reactivity of the highly strained electron-rich (BB)-carboryne fragment with small molecules was probed by reactions with electrophiles. The carboryne carboranyl transformations reported herein represent a new mode of cooperative metal ligand reactivity of boron-based complexes.