INDO MO Calculations of the Conformational Dependence of the vicinal ¹³C,H Spin–Spin Coupling Constant in Propane

Molecular orbital theory at the INDO level of approximation is used to calculate the Fermi contact contribution to three-bond carbon–proton coupling constants in propane. The calculations predict a dihedral angle dependence of 3 J( 13 C,H) in the 13 C—C—C—H fragment similar to that observed for 3 J(H,H), 3 J( 19 F,H), and for 3 J( 31 P,H) in the saturated X—C—C—H fragments.