Maximum bond order hybrid orbitals II. Correlativity with C-H and C-C spin-coupling constants

The excellent correlativity between the maximum bond order hybrid orbitals and the nuclear spin-spin coupling constants of directly bonded C-H and C-C is shown in the present paper. The maximum bond order hybrid orbital procedure is performed by use of the first-order density matrices obtained from CNDO/2 calculation to get the bonding hybrid orbitals and the corresponding maximum bond orders for a number of hydrocarbons and hetero-substituted hydrocarbons. The relations between the obtained calculation results and the experimental coupling constants are examined by using the basic relationships proposed by Muller and Pritchard, by Maksic et al. and by Gil, and summarized in the concrete relationships which are the most suitable for the maximum bond order hybrid orbital calculation. The obtained relationships combined with the maximum bond order hybrid orbital calculation is quite successful in predicting substituent effects on the C-H and C-C coupling constants in molecules which contain no substituents of the -I^- type.