Abstract: In this paper,a general relationship between the nuclear spin-Spin coupling con-stants(¹J_AB) across one bond and the s-character of hybrid orbitals and atomic net charges of atonis A and B is foimulated. The relationship obtained is applied to calcu-lation of the α-C-H coupling constants:¹J_CH for a series of substituted hydrocarbons by use of the CNDO/2 molecular orbital approximation and natural hybrid orbital scheme.It is verified that the J_CH values are crudely correlated with carbon hybridiZation and bond polarity.The latter becomes important for α-C-H coupling constants for liydrocarbons containing heteroatoms or substituents.Some discussions concerning the ealculatcd results and the factors which affect the coupling constants are also reported.

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