¹⁹F Coupling Constants Table

The fluorine-19 (¹⁹F) nucleus exhibits significant spin-spin coupling with neighboring nuclei, providing valuable structural information. The coupling constant (J) quantifies this interaction, measured in hertz (Hz), and reflects the magnetic interaction between ¹⁹F and other nuclei, such as ¹H, ¹³C, or other ¹⁹F atoms. The magnitude and pattern of J-couplings offer insight into bond connectivity, hybridization, and stereochemistry.

Below is a comprehensive table summarizing the ¹⁹F homonuclear couplings of various functional groups and fluorinated compounds.

Typical ¹⁹F Coupling Constants

Coupled Nuclei	Example Compound	Typical J-Value (Hz)	Description
19F-1H	CH3F	45 to 50	Direct coupling; largest J due to high gyromagnetic ratio of 1H
19F-13C	CF4	240 to 320	Strong coupling through a single bond
19F-12C	CF3H	Not observed	12C has no nuclear spin; hence no coupling
19F-19F	CF2=CF2	220 to 250	Large coupling observed for geminal or vicinal fluorines
19F-31P	PF3	700 to 1200	Strong coupling due to direct bond and high magnetic moment of 31P
19F-15N	NF3	10 to 20	Moderate coupling, dependent on bond angles and hybridization
Vicinal 19F-1H	CH2FCH3	5 to 10	Smaller coupling due to three-bond interaction
Long-range 19F-1H	Aromatic systems (C6H4F)	0.5 to 3.0	Coupling decreases rapidly with increasing bond distance
19F-31P (two bonds)	PF2(CF3)	60 to 90	Smaller coupling over two bonds
19F-19F (four bonds)	CHF=CF2	5 to 12	Long-range coupling common in conjugated systems

Fluorinated Compounds Coupling Constants

Compound	Coupling Constant (Hz)
(CF3CF2)2NCF3	10.2
(CF3CF2)2NCF3	15.18
(CF3CF2)2NCF3	6.8
[CF3CF2]3N	13.6
CF3CF2N[CF3]2	<1
CF3CF2N[CF3]2	16
CF3CF2N[CF3]2	6
(CF3CF2)2O	3.4
(CF3]3CF	1.4
CF3CF2H	2.8
CF3CFH2	15.5
CF3CF2CHF2	4.5
CF3CF2CHF2	7.3
CF3CF2CH2F	15.2
CF3CF2CH2F	7.9
CF2Cl.CF2.CH2F	15.1
CF2Cl.CF2.CH2F	7.7
CF2Cl.CF2.CH2F	3.9
CF2Br.CF2.CH2F	15.5
CF2Br.CF2.CH2F	7.7
CF2Br.CF2.CH2F	3.9
CFFBr.CHFBr	21
CFFBr.CHFBr	24
CFFBr.CHFBr	174
CFFBr.CHFCl	18
CFFBr.CHFCl	18
CFFBr.CHFCl	177
CFFBr.CFClBr	13
CFFBr.CFClBr	14
CFFBr.CFClBr	159
CFF(SiCl3).CFClBr	16.8
CFF(SiCl3).CFClBr	16.8
CFF(SiCl3).CFClBr	343
CF3.CFF.CFICl	270.4
CFF=CFCl	76
CFF=CFCl (cis)	56
CFF=CFCl (trans)	116
CFCl=CFCl (cis)	37.5
CFCl=CFCl (trans)	129.57
CFF=CFCF3	57
CFF=CFCF3 (cis)	39
CFF=CFCF3 (trans)	116
CFF=CFCF3 (trans)	8
CFF=CFCF3 (cis)	22
CFF=CFCF3	13
(cyclopropane) CH2.CFF.CHCH3	157
(cyclobutane) CH2.CFF.CCl2.CCl2	187
(cyclobutene) CFF.CH(C2H5).CCl2=CCl	192
(cyclobutane) CFF.CFF.CH2.CHCClH2	230
(cyclobutane) CFF.CFF.CH2.CHCClH2	240
(cyclohexane) CFH.CFH.CFH.CFH.CFH.CFF	284

Listed Coupling constant values pertain to Fs shown in bold.

Applications of ¹⁹F Coupling Constants

The study of ¹⁹F coupling constants enriches the analytical utility of NMR spectroscopy, providing a multidimensional approach to understanding molecular structure and dynamics.

• Structural Elucidation: J-coupling patterns help confirm bond connectivity, particularly in fluorinated pharmaceuticals, polymers, and agrochemicals.
• Conformational Analysis: The magnitude of vicinal J-couplings is sensitive to dihedral angles, enabling studies of molecular conformation and stereochemistry.
• Isotope Studies: Couplings with ¹⁵N, ³¹P, and ¹³C provide isotopic information in multinuclear NMR experiments.
• Quantitative Analysis: The J-coupling constants in fluorinated compounds can assist in calculating electron density distribution and bond strength.