Flip-flops in fluorinated o-cresol

Ab initio geometry optimizations are used to investigate the side chain fluorinated cis o-cresols, HOC6H4CH3−nFn (n=1, 2, and 3). The three ground states are found to contain hydrogen bonded hexagon, which may flip flop between two equivalent positions relative to the phenyl ring. In the cases n=2 and n=3 the activation energy for the flip-flop is about the same and less than 1 kJ/mol, whereas it is an order of magnitude higher for n=1. The difference in activation energies is associated with the dynamics of the flip-flop and the stoichiometry of the cresol.