Borotropy: The Mechanism of Boron Transfer Between Adjacent N‐Atoms of Pyrazol‐1‐yl Rings.

This work examines theoretically the problem of the migration of borane groups between the nitrogen atoms of pyrazolyl rings. We have studied as a model the BH2 pyrazol‐1‐yl derivatives to determine the effects of substituents on the pyrazole ring; also 1‐(9‐borabicyclo[3.3.1]nonan‐9‐yl)‐1H‐pyrazoles to compare the calculated barriers with the experimental ones as well as to determine steric effects, i. e., how the buttressing effect increases the rate. The interacting quantum atoms methodology has been used for partitioning the energy of the systems in their stationary points into the contribution of pyrazole and BH2 group and their mutual interaction. [ABSTRACT FROM AUTHOR]