Abstract: The novel generalized correlation of the nuclear spin-spin coupling constants with the atomic hybrids and net charges is employed to give new concrete relationships for calculating the directly bonded carbon-carbon and carbon-phosphorus coupling constants by use of the natural hybrid orbital procedure together with the MNDO/EHMO calculation.The calculated values are well in agreement with the experimental data, which suports the idea that the hybridization and bond polarity, and the Fermi contact term are dominant factors in determining carbon-carbon and carbon-phosphorus spin-spin coupling constants across one bond.Thus one is able to interpret and calculate the ¹J_CC and ¹J_CP values based on the simple valence bond theory.

Key words: Nuclear spin-spin coupling, Coupling constants, Hybrid orbitals, s-Characters, Net atomic charges