Potential energies were calculated for a series of methylated triarylborons considering interactions between all nonbonded atoms and pi‐electron resonance energies. All nonbonded interactions were estimated using modified Buckingham (exp‐six) potentials obtained from the literature; pi‐electron energies were calculated using simple molecular‐orbital theory. The resulting predictions of stable geometries were compared with those derived from proton magnetic‐resonance chemical shift data. All calculations were performed using a rigid geometric framework permitting only rotation of aryl groups. Reasonable agreement was found for several of the molecules studied; however, a number of discrepancies indicate certain inadequacies in the present treatment. In particular, future refinements must include the possibility of bond bending.
For tri‐1‐(2‐methylnaphthyl)boron, temperature dependence of the NMR spectra was indicative of rotational isomerism.
