A NORMAL COORDINATE ANALYSIS OF BORAZINE.

Utilizing a recent reassignment of the vibrational spectrum of borazine, -BH-NH-3, and isotopically labeled derivatives thereof, a normal coordinate analysis on this six-membered heterocycle has been performed. The calculated valence force field was adjusted to provide a reasonable fit for all of the available data. Initial calculations suggested the reassignment of one fundamental and also indicated that one of the seventeen observable normal vibrations could not be rigorously identified. When the entire set of suggested assignments for the normal vibrations of -BH-NH-3, -10BH-NH-3, -BH-ND-3, -10BH-ND-3, -BD-NH-3, -10BD-NH-3 and -BD-ND-3 was utilized in a simultaneous least-squares adjustment, the average error between all of the calculated and observed frequencies was 1.95. The calculated force constants are in agreement with recent judgments on the strength of the various bonds in the borazine molecule. The calculated potential energy distribution of the isotopically labeled derivatives indicates that the character of several BH and NH vibrations is altered substantially upon deuteration at either the boron or the nitrogen atoms. Displacements calculated for the parent borazine molecule reveal appreciable movement of the annular atoms out of the molecular plane. Author