Abstract A number of organomercury,-tin and-lead derivatives of m-and p-fluoro-substituted phenols and thiophenols of the type R n MOAr and R n MSAr have been prepared. The 19 F chemical shifts relative to fluorobenzene have been measured in various solvents for all these compounds. On the basis of the data obtained, the electronic features of the substituents R n MO and R n MS have been studied and compared with those of OH, CH 3 ...