6533b7cefe1ef96bd125798f
RESEARCH PRODUCT
A CNDO/2 study on the additivity and the nature of the non-additivity of the substituent effects on13C NMR shifts in chlorobenzenes and chlorophenols
Reino Laatikainensubject
CNDO/2chemistry.chemical_compoundAtomic orbitalComputational chemistryChemistryChlorobenzeneChemical shiftAdditive functionSubstituentGeneral Materials ScienceGeneral ChemistryElectronCarbon-13 NMRdescription
The general correlation between the electron densities and the 13C NMR chemical shifts is found to be quite poor in the cases discussed. The non-additivities of the substituent effects on the chemical shifts and the CNDO/2 electron densities correlate only weakly. However, when the electron densities are made specific to different types of atomic orbitals, the s electrons have a pronounced effect in all the models tested. This is explained by an indirect effect on the 〈1/r3〉 term of the p electrons. Good correlations are found between the sums of the chemical shifts and the corresponding sums of the substituent charge excesses. The different behaviour of OH and Cl substituents in the additivity of the substituent effects can be explained by their different back-bonding properties.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1980-11-01 | Organic Magnetic Resonance |