Features of the CH⋅⋅⋅N Weak Hydrogen Bond and Internal Dynamics in Pyridine–CHF₃

Abstract

All change: The dynamics, location, and hydrogen-bond features of CHF3 change drastically on going from the benzene–CHF3 to the pyridine–CHF3 molecular adduct. The barrier to internal rotation increases from almost nothing to ≈0.6 kJ mol−1; the CHF3 moiety moves into the ring plane from above, and a CH⋅⋅⋅N linkage replaces the CH⋅⋅⋅π contact (see figure).