Can the -CF3 Group Act as a Tight, Well-Defined Hydrogen Bond Acceptor? A Clear Crystallographic CF2-F···H-N+ Interaction Says Yes

J Org Chem. 2024 Jul 5;89(13):9681-9685. doi: 10.1021/acs.joc.4c00873. Epub 2024 Jun 18.

Abstract

The CF3 group is well noted for being noninteractive with other functional groups. In this Note, we present a highly rigid model system containing a significant hydrogen bonding interaction between a charged N-H donor and a CF3 acceptor that challenges this accepted wisdom. Spectroscopic and single crystal X-ray crystallography data characterize this interaction, consistent with a weak to moderate hydrogen bond that would be difficult to observe in an intermolecular system.