Reversibility of 1,4-Metal Migration in Cp*Rh^III and Cp*Ir^III Complexes

The (2-ethenyl-4-methylphenyl)­arylrhodium complex [Cp*Rh­{C₆H₃-2-(C­(Ph)CHPh)-4-Me}­(PMe₃)]­[BAr^F₄], which is formed from the vinyl-to-aryl 1,4-Rh migration of the 2-(<i>m</i>-tolyl)­ethenyl complex [Cp*Rh­{C­(Ph)C­(C₆H₄Me-<i>m</i>)­Ph}­(PMe₃)]­[BAr^F₄], is isomerized under mild conditions to the regioisomeric 2-ethenylphenyl complex [Cp*Rh­{C₆H₄-2-(C­(C₆H₄Me-<i>m</i>)CHPh)}­(PMe₃)]­[BAr^F₄] by way of a back-reaction to regenerate the 2-(<i>m</i>-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