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) [RF = F, CF3, CF2CF3] occurs by α-fluorine elimination to give the perfluoroalkylidene complexes Cp*(CO)IrCFRF; when RF = CF3, the E-isomer predominates, while when RF = CF2CF3, the Z-isomer is preferred. No β-fluorine elimination is observed in these reactions, but when no α-fluorines are present, reduction of Cp*Ir(CO)(CH2CF2RF)(I) [RF = F, CF3] occurs cleanly by β-fluorine elimination to afford a new route to the hydrofluoroalkene compounds Cp*Ir(CO)(CH2CFRF) [RF = F, CF3].