MECHANISM OF ELECTROPHILIC SUBSTITUTION WITH PARTICIPATION OF ION-PAIRS IN ORGANOMETALLIC CHEMISTRY (SE2 ION-PAIR MECHANISM)

A new mechanism SE2 ion pair) has been suggested for the reaction of organotin compounds with electron-withdrawing groups (R = 9-Me-fluorenyl, indenyl, PhCC etc.). It has been shown that some RSnMe3 compounds may undergo ionization or dissociation in polar solvents. In low-polar solvents optically active indenyl derivatives of tin racemize slowly but the rate of racemization is increased by addition of hexamethylphosphoric triamide. This result was explained by the loss of configuration when the ion pair R-Sn+Me3 reverts to the covalent form. © 1978.