Vicinal Coupling in Adjacent Protons

Vicinal coupling is the three-bond interaction between protons on neighboring carbons. It is a common feature in proton NMR and helps show how nearby C-H bonds are connected. Nuclear spin information is transferred mainly through electron spin interactions between adjacent C-H bond orbitals.

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Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons.

Nuclear spin information is primarily transferred via electron spin interactions between adjacent C–H bond orbitals.

This generally favors the antiparallel arrangement of spins, so ³J values are usually positive.