The importance of multicenter integrals in semiempirical calculations of nuclear spin-spin coupling constants. 2. Anisotropic coupling
A molecular orbital (MO) study of anisotropic nuclear spin-spin coupling is presented in terms of a semiempirical formulation with inclusion of all multicenter integrals in the Fermi contact, orbital, and spin-dipolar contributions. This formulation extends existing semiempirical MO theories to include the large class of coupling constant anisotropies involving protons. Calculations for representative molecules are based on the first-order polarization propagator approach, which is equivalent to coupled Hartree-Fock theory, and the semiempirical INDO MO level of approximation for the wave-functions. The calculated results agree with ab initio MO results, but the very large errors in most of the experimental data make detailed comparisons difficult. The asymmetry features of the anisotropic coupling tensors are also discussed. © 1984.
