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

In situ lithiation of HN( o ‐C 6 H 4 PPh 2 ) 2 (H[ 1a ]) or HN( o ‐C 6 H 4 P i Pr 2 ) 2 (H[ 1b ]) with n BuLi 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(η 4 ‐COD) ( 2a ) or 4‐coordinate [ 1b ]Ir(η 2 ‐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 LiBHEt 3 in the presence of 1 atm of H 2 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.