C(sp2)–F Oxidative Addition of Fluorinated Aryl Ketones by iPrPCPIr

The reaction of iPrPCPIrH4 (iPrPCP = κ3-2,6-C6H3(CH2P(iPr)2)2) with ≥2 equiv of 2,3,4,5,6-pentafluoroacetophenone (AP-F5) in aromatic solvents at room temperature leads to the hydrogenation of AP-F5 and formation of the corresponding 5-coordinate alkoxy hydride species (I) within several minutes. Heating at ≥120 °C quickly provides the cyclometalated trans C-H product iPrPCPIr(κ-O,C-OC8H3F4)H (III), which slowly isomerizes to the cis C-H product iPrPCPIr(κ-C,O-OC8H3F4)H (V). The fate of the fluoride during formation of III and V is not entirely clear, though the production of HF is implicated by significant glass etching and several crystal structures. When iPrPCPIrH4 is allowed to react overnight with ≥2 equiv of AP-F5 at room temperature, formation of C–F oxidative addition product iPrPCPIr(κ-O,C-OC8H3F4)F (II) is observed by 31P and 19F NMR spectroscopy. When iPrPCPIrH4 activated with tert-butylethylene is employed, formation of II occurs within 10 min. Analogous reactivity is observed with several oth...