α- and β-Fluorine elimination reactions induced by reduction of iridium-fluoroalkyl complexes.: Selective formation of fluoroalkylidene and hydrofluoroalkene ligands

Two-electron reduction of the perfluoroalkyl complexes Cp* Ir(CO)(CF2RF)( I) [R-F = F, CF3, CF2CF3] occurs by R-fluorine elimination to give the perfluoroalkylidene complexes Cp*(CO) Ir=CFRF; when R-F=CF3, the E-isomer predominates, while when R-F = CF2CF3, the Z-isomer is preferred. No beta-fluorine elimination is observed in these reactions, but when no alpha-fluorines are present, reduction of Cp* Ir(CO)(CH2CF2RF)(I) [R-F = F, CF3] occurs cleanly by beta-fluorine elimination to afford a new route to the hydrofluoroalkene compounds Cp* Ir(CO)(CH2=CFRF) [R-F = F, CF3].