The equilibrium C-H bond length

The equilibrium C-H bond length has been determined up to now for about 40 polyatomic molecules. These data are used to demonstrate the existence of quantitative correlations betweenr_e(C-H), isolated C-H bond stretching frequency and average distancer_g. It is also shown that ab initio calculations are often reliable to calculate the absolute value ofr_e(C-H), if an empirical correction is made. Some other correlations are also discussed. Finally, accurater_e(C-H) values are predicted for simple molecules.