The cis-insertion of diphenylacetylene into an exo-polyhedral boron–hydrogen bond of a molybdenacarbaborane cage

The η2(4e)-alkyne bis(trimethylphosphite) substituted complexes [closo-3-(η2-alkyne)-3,3-{P(OMe)3}2 31,2-MoC2B9H11] react with alkynes to form either monophosphite bis(alkyne) or mixed alkyne complexes [closo-3,3-(η2-alkyne)(η2-alkyne)-3-{P(OMe)3}-3,1,2-MoC2B9H11]; however, an attempt to extend the reaction to the bis(diphenylacetylene) system resulted in a novel cis-insertion of the alkyne into an exo-polyhedral B–H bond, which is explained by a bimetallic reaction pathway.