CL-35 CL-37 ONE-BOND ISOTOPE EFFECTS ON C-13 CHEMICAL-SHIFTS IN A SERIES OF PARASUBSTITUTED CHLOROBENZENES/

One-bond isotope shifts of Cl-35/Cl-37 natural abundance chlorine isot opomers were measured in the 75.4 MHz C-13 NMR spectra of a series of para-substituted chlorobenzenes. The high-field isotope shift effect ( 1) Delta(13)C(Cl-37) was established from the relationship between the chlorine isotopomeric ratio and the carbon peak intensities. It was f ound that the (1) Delta(13)C(Cl-37) values are in the range of - 4.0 t o - 5.2 ppb. The isotope shifts tend to decrease as the electron-attra cting character of the substituent increases, providing a linear corre lation between the isotope shift and the chemical shift of the chlorin e-bearing carbon.