Quadratic potential functions for the boron trihalides

General quadratic compliance constants have been evaluated for the boron trihalides using frequency data and Coriolis coupling constants obtained from a variety of sources. Coriolis data from band contour analysis are too imprecise to help determine the E′ symmetry potential constants. Solutions obtained using Cyvin's Coriolis constants appear to be reasonable on the basis of trends in the valence compliants and interaction displacement coordinates. The semiempirical SCF-MO scheme MNDO has been employed to establish prior constraints of the interaction displacement coordinates in the estimate of the quadratic potential constants for BF₃ and BCl₃.