Effect of substituents on electronegativities of Ar3Si and Ar3Sn groups: Comparison of the results of ab initio quantum-chemical calculation and F-19 NMR data for Ar(3)MQC(6)H(4)F-4 compounds

Ab initio calculations of group electronegativities (chi) of Ar3Si and Ar3Sn groups containing 13 types of meta-, para- and polysubstituted phenyl groups have been performed. Calculated values of chi(Ar3Si) and chi(Ar3Sn) correlate better with the sigma(0) Taft constants than with the sigma Hammett constants, which is indicative of the inductive nature of the effect of aryl groups on electronegativities of Ar(3)M groups. Good correlations have been found between F-19 chemical shifts and the corresponding values of chi(Ar3Si) and chi(Ar3Sn) for the Ar3SiC6H4F-4, Ar3SnC6H4F-4, Ar3SnCH2C6H4F-4, and Ar3SnSC6H4F-4 compounds.