Catalytic olefin hydrogenation using N-heterocyclic carbene–phosphine complexes of iridium

SambVca: A Web Application for the Calculation of the Buried Volume of N‐Heterocyclic Carbene Ligands

“…In many cases, use of NHC ligands results in smoother reaction conditions and new reactivity. The most noticeable examples are in the fields of Rucatalysed olefin metathesis, [23][24][25][26][27][28][29] Ir-catalysed hydrogenation [30][31][32] or Pd-catalysed C-C coupling reactions, [33][34][35] and/or have led to unexpected reactivity, as in the case of Au-catalysed reactions. [36,37] Further, the skeletons of satu-rated NHCs are key structural features for the introduction of asymmetry in the NHC ring, which opens the door to the use of chiral NHCs in asymmetric synthesis.…”

How Important Is Backbonding in Metal Complexes Containing N‐Heterocyclic Carbenes? Structural and NBO Analysis

“…Since then, the impact of NHCs and the related diaminocarbenes in organometallic chemistry has been unquestionable. [4][5][6][7][8] They [9] have been used in several metal-based catalysts for a large variety of reactions such as hydrogenations, [10,11] hydrosilylations, [12,13] olefin metathesis, [14][15][16][17] and C-C coupling reactions. [18][19][20][21][22] The large number of applications is due in part to the fact that complexes of these ligands are kinetically robust towards decomposition reactions.…”

Asymmetric Hydrogenation of Olefins Using Chiral Crabtree-type Catalysts: Scope and Limitations

“…21 Crabtree and co-workers 34 Parahydrogen induced polarization (PHIP) 1 H NMR experiments indicated that a dihydride mechanism was operating, but other mechanisms could not be ruled out. 35 Roseblade and Pfaltz also considered a related mechanism, 36 to form H which, by coordination of another alkene and a solvent molecule, reforms E (the suggested catalyst resting state). The migratory insertion (step F → G) was calculated to have the only significant energy barrier and was proposed to be the rate-determining step.…”