Catalytic Olefin Hydrogenation Using N‐Heterocyclic Carbene—Phosphine Complexes of Iridium.

Abstract

Hydrogenation Hydrogenation O 0220 Catalytic Olefin Hydrogenation Using N-Heterocyclic Carbene-Phosphine Complexes of Iridium. -Novel complexes having a combination of phosphine and N-heterocyclic carbene ligands are found to be highly reactive towards the homogeneous catalytic hydrogenation of simple olefins, including hindered substrates. -(VAZQUEZ-SERRANO, L. D.; OWENS, B. T.; BURIAK*, J. M.; Chem.

Capping Arene Ligated Rhodium-Catalyzed Olefin Hydrogenation: A Model Study of the Ligand Influence on a Catalytic Process That Incorporates Oxidative Addition and Reductive Elimination

“…This half-order dependence on [4] suggests the possible formation of a dimeric Rh complex from 4. 52,53 For example, dissociation of the 5-NP FP ligand could form a chloride-bridged Rh dimer, which could serve as the catalyst precursor (see Supporting Information, section 6.3 for details). Consistent with this hypothesis, the rate dependence on [Rh] using [Rh(η 2 -C 2 H 4 ) 2 (μ-Cl)] 2 as the catalyst precursor for styrene hydrogenation revealed a halforder dependence (Figure 3C), and the observed rate is at least 10 times faster than the 4-catalyzed styrene hydrogenation under the same conditions.…”

Iridium Cyclooctene Complex That Forms a Hyperpolarization Transfer Catalyst before Converting to a Binuclear C–H Bond Activation Product Responsible for Hydrogen Isotope Exchange

“…This process has now been refined to extend the level of signal gain, 15−18 the range of applications, 19,20 the nuclei that can be polarized, 21−25 and the classes of substrates that can be employed. 26−28 So far, IrCl(COD)(IMes) 29 [IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene] 4 reflects one of the better SABRE catalysts because its ligand exchange rates match those of the spin-spin couplings associated with polarization flow, but slow catalyst activation can be a problem. 30,31 We set out here to develop a rapidly activating and readily available air-stable precursor for SABRE and now describe the ensuing observations.…”