C13 Splittings in Proton Magnetic Resonance Spectra. I. Hydrocarbons

Abstract

Indirect spin‐spin couplings between protons and C13 nuclei have been measured for a number of hydrocarbons. The results are interpreted on the basis of a simple semiempirical equation relating the coupling constants with the amounts of s character of the carbon‐atomic orbitals involved in the bonds. No evidence is found for a dependence of the coupling constants on supposed changes in ionic character of the bonds. An equation is also presented relating the coupling constants and the C–H internuclear distances. This provides a new indirect means of evaluating C–H distances, with a reliability apparently at least comparable with that of methods in current use.