Reversibility of 1,4-Metal Migration in Cp*RhIII and Cp*IrIII Complexes

The (2-ethenyl-4-methylphenyl)­arylrhodium complex [Cp*Rh­{C6H3-2-(C­(Ph)CHPh)-4-Me}­(PMe3)]­[BArF4], which is formed from the vinyl-to-aryl 1,4-Rh migration of the 2-(m-tolyl)­ethenyl complex [Cp*Rh­{C­(Ph)C­(C6H4Me-m)­Ph}­(PMe3)]­[BArF4], is isomerized under mild conditions to the regioisomeric 2-ethenylphenyl complex [Cp*Rh­{C6H4-2-(C­(C6H4Me-m)CHPh)}­(PMe3)]­[BArF4] by way of a back-reaction to regenerate the 2-(m-tolyl)­ethenyl complex intermediate followed by the rotation of the CC bond and the second 1,4-Rh migration, providing experimental evidence for the reversibility of the vinyl-to-aryl 1,4-metal migration.