The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in homonuclear coupling, nuclei of different elements interact in heteronuclear coupling.

Consider non-equivalent protons A and X that have excitation energies of A and X. The term J = 0 is used to indicate that they do not interact via coupling. Coupling between A and X results in the modification of their nuclear spin energy levels and is expressed as J ≠ 0. For the coupled spins of A and X, the energy required to excite proton A to a spin state parallel to proton X is slightly different from the energy required for it to become antiparallel to spin X.

From Chapter 8:

article

Now Playing

8.10 : NMR Spectroscopy: Spin–Spin Coupling

Interpreting Nuclear Magnetic Resonance Spectra

1.1K Views

article

8.1 : Chemical Shift: Internal References and Solvent Effects

Interpreting Nuclear Magnetic Resonance Spectra

531 Views

article

8.2 : NMR Spectroscopy: Chemical Shift Overview

Interpreting Nuclear Magnetic Resonance Spectra

1.3K Views

article

8.3 : Proton (¹H) NMR: Chemical Shift

Interpreting Nuclear Magnetic Resonance Spectra

1.4K Views

article

8.4 : Inductive Effects on Chemical Shift: Overview

Interpreting Nuclear Magnetic Resonance Spectra

1.0K Views

article

8.5 : π Electron Effects on Chemical Shift: Overview

Interpreting Nuclear Magnetic Resonance Spectra

997 Views

article

8.6 : π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds

Interpreting Nuclear Magnetic Resonance Spectra

1.1K Views

article

8.7 : ¹H NMR Chemical Shift Equivalence: Homotopic and Heterotopic Protons

Interpreting Nuclear Magnetic Resonance Spectra

2.2K Views

article

8.8 : ¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons

Interpreting Nuclear Magnetic Resonance Spectra

1.3K Views

article

8.9 : ¹H NMR Signal Integration: Overview

Interpreting Nuclear Magnetic Resonance Spectra

1.2K Views

article

8.11 : ¹H NMR Signal Multiplicity: Splitting Patterns

Interpreting Nuclear Magnetic Resonance Spectra

4.8K Views

article

8.12 : Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule

Interpreting Nuclear Magnetic Resonance Spectra

1.1K Views

article

8.13 : Spin–Spin Coupling Constant: Overview

Interpreting Nuclear Magnetic Resonance Spectra

834 Views

article

8.14 : Spin–Spin Coupling: One-Bond Coupling

Interpreting Nuclear Magnetic Resonance Spectra

898 Views

article

8.15 : Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

Interpreting Nuclear Magnetic Resonance Spectra

890 Views

See More

We use cookies to enhance your experience on our website.

By continuing to use our website or clicking “Continue”, you are agreeing to accept our cookies.

Learn More