The effects of fluorine substitution on the ³⁵Cl NQR spectra of fluoroaromatic compounds containing element-chlorine bonds

The ³⁵Cl NQR spectra of pentafluorosubstituted derivatives of benzene C₆F₅X (X = NPCl₃, CONPCl₃, SO₂NPCl₃, NCCl₂, SCl, COCl, SO₂NCl₂, CONCl₂, PCl₂, SO₂Cl) and phosphazocompounds (dimers, [RNPCl₃]₂; R = C₆F₅, C₆H₅, 2,3,5,6-tetrafluoropyridyl) have been recorded and interpreted. On passing from phenyl to pentafluorophenyl derivatives, the ³⁵Cl NQR frequencies increased. The influence of the relative numbers and positions of the fluorine atoms in the benzene ring on the ³⁵Cl NQR frequencies of fluoro-containing benzoyl chlorides has been discussed. The results are explained in terms of charge alteration on chlorine under the influence of the aromatic fluorine atoms. A linear correlation has been found between ³⁵Cl NQR frequencies of pentafluorophenyl derivatives and those of their hydrocarbon analogues. A relationship between elecronegativity of the element and the ionic character of the element-chlorine bond has been revealed. The reactivities of pentafluorophenyl and phenyl derivatives containing element-chlorine bonds have been predicted using the ν_Cl values.