Homogeneous hydrogenation of imines catalyzed by rhodium and iridium complexes: Kinetics and mechanism of the hydrogenation of N-(β-naphthyl methylene) aniline using [Ir(COD)(PPh3)2]PF6 as catalyst precursor

✍ Scribed by V. Herrera; B. Muñoz; V. Landaeta; N. Canudas

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 168 KB
• Volume: 174
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/s1381-1169(01)00197-2

✦ Synopsis

The regioselective hydrogenation of some imines to the corresponding amines is efficiently catalyzed by [Ir(COD)(PPh 3 ) 2 ]PF 6 (1) and [Rh(COD)(PPh 3 ) 2 ]PF 6 (2) at 60 • C and 200 psi of H 2 . The kinetics of the hydrogenation of N-(␤-naphthyl methylene) aniline (N␤NA) with [Ir(COD)(PPh 3 ) 2 ]PF 6 in tetrahydrofuran (THF) have been studied. The experimentally determined rate law is

where k cat = (2.2 ± 0.3) × 10 3 M -2 s -1 at 323 K and the corresponding activation parameters are: H • = (4.0±0.4) kcal mol -1 ; S • = (-32±2) e.u.; G • = (14±2) kcal mol -1 . A catalytic cycle is proposed on the basis of the kinetic experiments and some NMR data.