Carbon−Fluorine Bond Activation Coupled with Alkynyl Migration to Give Fluorinated Allenyl Complexes of Iridium

The propynyl(perfluoropropyl) iridium complex Cp*Ir(PMe3)(CF2CF2CF3)(C⋮CCH3) has been prepared
and crystallographically characterized. It reacts with lutidinium iodide to afford α-CF bond activation
and propynyl migration to carbon, to give the allenyl complex Cp*Ir(PMe3)(I)[(CH3)CCCF(CF2CF3)] as a single diastereomer, for which the relative configurations at Ir and at the helical allenyl ligand
were shown to be (SIr,M)(RIr,P) by X-ray crystallography. On standing in solution the (SIr,M)(RIr,P)
diastereomer rearranges slowly to the thermodynamically more stable (RIr,M)(SIr,P) diastereomer, also
characterized crystallographically, illustrating that the initial diastereomer is formed under conditions of
kinetic control. A detailed mechanism is presented to rationalize these observations, and comparisons to
previous CF activation/CC coupling reactions are made.