A molecular orbital theory of proton spin–spin coupling constants

Abstract

If equivalent orbitals are used in the description of carbon–hydrogen bonds, a very simple formula for proton–proton coupling constants in hydrocarbons may be derived. Only two MO parameters, one for the π-interactions of carbon hybrid orbitals and one for the interaction of orbitals on the same atom, are needed to reproduce most of the observed trends in the hyperfine splitting of proton magnetic spectral lines. Addition of a further parameter makes it possible to estimate the actual magnitude of coupling constants. The scalar interaction of protons appears to take place largely by means of π-interactions, often within the so-called σ-skeleton of a molecule.