Stereodynamics of Substituted Neopentanes

Article abstract of DOI:10.1021/jo00181a008

tert-Butyl rotation barriers have been measured in four monosubstituted neopentanes (Me3CCH2X, X=Me, Cl, Br, I) by using 270-MHz 1H dynamic NMR spectroscopy.The barrier depends on X in the order: Me < Cl = ca.Br = ca.I.As a complement to the experimental DNMR data, Allinger's MM2 molecular mechanics program (1980 force field) was used to calculate optimized equilibrium geometries and tert-butyl rotation barriers for the four compounds.The MM2 barriers are compared to previously reported MM1 barriers.