Complexes IrCl(CO)PN and IrCl(CO)PCN, where PN is o-(diphenylphosphino)-N,N-dimethylaniline and PCN is o-(diphenylphosphino)-N,N-dimethylbenzylamine, have been prepared. The compounds react with HCl and with a mixture of MeI and iodide to give IrHCl2(CO)PN, IrHCl2(CO)PCN, IrMeI2(CO)PN, and IrMeI2(CO)PCN. The relative order of effectiveness for the catalytic hydrogenation of hexene-1 is IrCl(CO)PCN > IrCl(CO)PN > IrCl(CO)(PPh3)2. The compound IrCl(CO)PCN is conformationally mobile because of inversion of the six-membered ring. Values for Ea, ΔH‡, and ΔS‡ are 18.0 kcal/mol, 17.5 kcal/mol, and 15.3 cal/(deg mol), respectively, which compare to values of 8.8 kcal/mol, 8.3 kcal/mol, and -17.4 cal/(deg mol) for RhCl(CO)PCN. Equilibrium measurements of [Ir(III)]/[Ir(I)] for the addition of benzoic acid to IrCl(CO)PCN, IrCl(CO)PN, and IrCl(CO)(PPh3)2 show that there is little difference in the basicities of the three metal centers. The compounds IrCl(CO)(PCN)2 and IrCl(CO)(PO)2 are also described, where PO is o-(diphenylphosphino)anisole.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry