Negative Nuclear Spin-Spin Coupling Constants for Aromatic Protons

Abstract

Valence bond theory and observed hyperfine splitting data are used to calculate proton‐proton spin‐spin couplings that arise through long range correlation of π‐electron spins in even alternate aromatic hydrocarbons. In benzene and naphthalene calculated spin coupling constants are positive for protons separated by an odd number of carbon‐carbon bonds and are negative for protons separated by an even number of carbon‐carbon bonds.