SCF MO CI STUDIES OF CONTACT NUCLEAR SPIN-SPIN COUPLING .I. PI-ELECTRON COUPLING BETWEEN PROTONS

A theoretical study of ir-electron coupling between protons is presented in terms of the nuclear spin-spin coupling formalism which uses the generalized product approximation with intergroup configuration interaction. Calculations are performed for several unsaturated and aromatic hydrocarbons in which the x-electron systems are described by self-consistent-field molecular-orbital (SCF MO) wavefunctions in the variable-β modification of the Pariser-Parr-Pople method. Coupling constant results are found to be quite sensitive to the inclusion of configuration interaction (CI) in the triplet manifold of the -4-electron system. Calculated values are compared with the experimental results.