Perturbation of 1JC,F Coupling in Carbon-Fluorine Bonds on Coordination to Lewis Acids: A Structural, Spectroscopic, and Computational Study.

A lithiated m-terphenyl ligand bearing fluorine atoms at the ortho positions of the flanking aryl rings was synthesized and characterized using single crystal X-ray diffraction, variable-temperature multinuclear NMR spectroscopy, and computational methods. Changes in 1JC,F on coordination to lithium as a spectroscopic observable parametrizing the strength of the C-F···Li interaction are described, and a general, qualitative relationship between C-F bond lengths, Δ1JC,F values, and the extent of C-F bond activation as a result of Lewis acid coordination is proposed.