Rhodium and Iridium β-Diiminate Complexes – Olefin Hydrogenation Step by Step

✍ Scribed by Peter H. M. Budzelaar; Nicolle N. P. Moonen; René de Gelder; Jan M. M. Smits; Anton W. Gal

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 738 KB
• Volume: 2000
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/(sici)1099-0682(200004)2000:4<753::aid-ejic753>3.0.co;2-v

✦ Synopsis

The bulky β-diiminate ligands [(2,6-C 6 H 3 X 2 )NC(Me)CHC(-Me)N(2,6-C 6 H 3 X 2 )] -(X = Me, L Me ; X = Cl, L Cl ) have been found to be effective in stabilizing low coordination numbers (CN) in Rh and Ir complexes. The 14-e complex L Me Rh(COE) (COE = cyclooctene) has a three-coordinate T-shaped Rh environment and is nonagostic. Coordinative unsaturation is avoided by incorporation of a small ligand (e.g. N 2 , MeCN, olefins), by the intramolecular coordination of a chlorine atom in L Cl Rh(COE), or by an agostic interaction in L Me Rh(norbornene). In solution at room temperature, L Me Rh(COE) undergoes rapid isomerization according to the allyl hydride mechanism; the corresponding 2,3-dimethylbutene complex actually prefers the allyl hydride structure.