Activation of ethylene and ammonia at iridium: C–H versus N–H oxidative addition

Abstract

The ammine complexes cis-trans-[Ir(4-C₅NF₄)(H)₂(NH₃)(PiPr₃)₂] (3) and cis-[Ir(4-C₅NF₄)(H){(E)-(MeO₂C)CCH(CO₂Me)}(NH₃)₂(PiPr₃)] (5) are generated on reaction of cis-trans-[Ir(4-C₅NF₄)(H)₂(PiPr₃)₂] (1) or of the vinyl compound trans-[Ir(4-C₅NF₄)(H){(E)-(MeO₂C)CCH(CO₂Me)}(PiPr₃)₂] (4) with NH₃, respectively. Photolysis of 5 gives complex [Ir(4-C₅NF₄)(H){κ²-(C,O)-(Z)-(MeO₂C)CCH(COOMe)}(NH₃)(PiPr₃)] (6). Treatment of the ethylene compound trans-[Ir(4-C₅NF₄)(C₂H₄)(PiPr₃)₂] (2) with ammonia yields C–H activation products such as the hydrido vinyl species trans-[Ir(4-C₅NF₄)(H)(C₂H₃)(NH₃)(PiPr₃)₂] (7) and the cyclometallation products [Ir(4-C₅NF₄)(H)(NH₃){κ²-(P,C)-CH₂CH(CH₃)PiPr₂}(PiPr₃)] (8a, 8b). A subsequent reaction leads to the generation of the binuclear oxidative addition product of ammonia [Ir(4-C₅NF₄)(H)(μ-NH₂)(NH₃)(PiPr₃)]₂ (9).