Lastly, Al(CN) 3 was considered to propose possible B(CN) 3 for the sake of verifying the valence hypothesis since Al is trivalent and belongs to IIIA group. The resulting cohesive energy of -1.341 eV, within range of the CuCN-type BCN (Table ) indicates a non-favorable structure, thus confirming that BCN is not a 'cyanide'.