19F spectra—structure correlations of fluorinated quaternary phosphonium salts

The ¹⁹F NMR chemical shifts and geminal FCP and FCH coupling constants are reported for a number of fluorinated quaternary phosphonium salts of the type documentclass{article}pagestyle{empty}begin{document}$ [{rm R}_3 mathop {rm P}limits^ oplus {rm CFXY}]{rm Z}^ ominus $end{document}, where generally R = alkyl or aryl; X, Y = hydrogen or halogen and Z = halogen. Spectral parameters remain relatively unaffected upon variance of R, Z^?, and/or solvent, except when R is a bulky alkyl group. Linear relationships accurately describe the correlation between the summation of the electronegativities of X and Y, or simply of Y if X = F, and the ¹⁹F NMR chemical shift and geminal FCP coupling constant; geminal FCH coupling constants show no such dependence. These relationships are of demonstrated analytical value, particularly for the purpose of spectral prediction.