MO AND VIBRATIONAL NORMAL COORDINATE CALCULATIONS OF 1,1,4,4,-TETRAMETHYL-1,4-DIAZONIA-2,5-DIBORATACYCLOHEXANE

All-valence-electron IEHT and CNDO/2 molecular orbital calculations and an infrared vibrational normal coordinate analysis were carried out for the study of the bonding in the title compound with its six-membered ring, repeating, all-four-coordinated NBC sequence. Results of these calculations agree qualitatively with one another as well as with the residual electron density map calculated from the observed and calculated structure factors in an X-ray structure determination, which showed that the BC bond is relatively stronger than the BN bond in this molecule. The results of MO calculations also indicate that partial electron transfer from the nitrogen to the boron atom has occurred in the formation of the boronnitrogen bond. The stretching force constants for the BN and BC bonds are 2.19 and 3.33 mdyn Å-1, respectively. © 1979.