We have attempted to characterize the cyano and the isocyano groups by stressing their analogy to the CNÂ radical. Some cyano compounds (like vinyl isocyanide, methyl cyanide, and methyl isocyanide) have been investigated by performing SCF computations. In addition R CN and CN R compounds have been simulated by perturbing the CNÂ with positive or negative point charges. The simulation reveals that classical electrostatic perturbation by point charges induces a two way charge transfer, characteristic of R CN or NC R compound computed in the SCF approximation. In addition, the analysis of dipole moment for the point charge perturbed CNÂ gives results which explain the high dipole moment present in many R CN or CN R compounds. © 1969, American Institute of Physics. All rights reserved.