Modification of cobalt bis(dicarbollide) ion with nitrile groups on carbon atoms: a unique low-temperature skeletal rearrangement due to specific electron-donor character of the CN substitution.

Herein we report on synthesis and stereochemistry of mono- and isomeric dinitrile derivatives of [(1,2-C2B9H11)2-3,3’-Co]- ion. The shape and electronic properties of CN groups are apparently able to surmount the strain associated with substitution of two vicinal carbon positions. Due to electron donation to the cage, this results in a substituent induced rearrangement of one of the carbon atoms to the upper pentagon belt. The molecular structure of this isomer is confirmed by sc-XRD and DFT chemical computations.