Amido PNP complexes of iridium: Synthesis and catalytic olefin and alkyne hydrogenation

Abstract

AbstractIn situ lithiation of HN(o‐C6H4PPh2)2 (H[1a]) or HN(o‐C6H4PiPr2)2 (H[1b]) with nBuLi in THF at −35°C followed by addition of [Ir(μ‐Cl)(COD)]2 (COD = 1,5‐cyclooctadiene) in toluene at −35°C generates 5‐coordinate [1a]Ir(η4‐COD) (2a) or 4‐coordinate [1b]Ir(η2‐COD) (2b), respectively. Oxidative addition of N‐H in H[1b] to [Ir(μ‐Cl)(COD)]2 affords square pyramidal [1b]Ir(H)(Cl) (3b). Metathetical reaction of 3b with LiBHEt3 in the presence of 1 atm of H2 in toluene produces [1b]Ir(H)2 (4b). Both 2a and 4b are active for catalytic hydrogenation of olefins and alkynes under extremely mild conditions.