33S NMR Spectroscopy. 2. Substituent Effects on 33S Chemical Shifts and Nuclear Quadrupole Coupling Constants in 3- and 4-Substituted Benzenesulfonates. Correlation between Chemical Shifts and Nuclear Quadrupole Coupling Constants

Substituent effects on 33S NMR parameters in 3-XC6H4SO3Na (X = NO2, NH3 +, CF3, SO3 -, OH, H, CH3, NH2, and O-) have been studied. The results obtained confirm that 33S chemical shifts and line widths depend upon the electronic properties of substituents present on the aromatic ring. The trends observed are consistent with the behavior found for previously reported 4-substituted benzenesulfonates, whose list has been now enlarged to include ionic substituents (O-, NH3 +, NH(CH3)2 +, SO3 -). Dual substituent parameter analysis of 33S nuclear quadrupole coupling constants using charged and uncharged substituents has been performed. A linear relationship between 33S chemical shifts and nuclear quadrupole coupling constants demonstrates that in 3- and 4-substituted benzenesulfonates substituents affect 33S NMR parameters in the same way, probably by expansion or contraction of p valence shell electrons around the sulfur nucleus. 17O NMR data suggest that sulfur d orbitals are little effective in transmitting substituent effects.