Stoichiometric and Catalytic Reactions of Thermally Stable Nickel(0) NHC Complexes

Abstract

Although there are many organic reactions that are catalyzed by either Ni 0 or Pd 0 complexes, in comparison with the case for Pd 0 there has been significantly less work studying coordinatively unsaturated Ni 0 complexes. Here, we develop a simple synthetic route for preparing a number of thermally stable NHC-supported Ni 0 hexadiene complexes in good yield. We examine the stoichiometric reactivity of one of these species and demonstrate that the coordinated hexadiene moiety is labile and can be replaced with a variety of different ligands, including CO, phosphines, isonitriles, and olefins. In addition, we show that the Ni 0 hexadiene complexes are relatively rare examples of homogeneous first-row transition-metal catalysts for the hydrogenation of olefins.

Nickel N-heterocyclic carbene complexes and their utility in homogeneous catalysis

“…The direct method yielded the following complexes, (302−303), [117] (304), [118] (305), [117] (307) The oxidation method (Scheme 15) was used for preparing the (306), [28e] (313), [36] (314−319), [118] (320), [36,118] (321−324) [118] and (325) [76] complexes from the reaction of Ni(COD) 2 and allyl halides.…”

“…Hydrogenation of olefins as catalyzed by Ni−NHC complexes.The olefin adduct of the nickel(0)−NHC complexes(46) and(87−90) carried out the hydrogenation of various cyclic and acylic olefins[36].…”

Heterogeneous Olefin Hydrogenation Enabled by a Highly‐Reduced Nickel(−II) Catalyst Precursor

“…[13] Hazaria nd Driess prepared heteroleptic carbene/silylenec omplexes B and C,w hich are very active hydrogenation catalysts. [14,15] Catalyst D reported by Chirik and co-workersc onstitutes the current state of the art in catalytic hydrogenations of sterically hindered tri-and tetra-substituted olefins. [16] The active catalysti sa ssembled from the combinationo fn ickel(II) bis(octanoate), pinacolb orane, and an a-diimine ligand.…”

Addition of Pt(IPr) Groupings to Ru5 Carbide Gives New Mixed-Metal Pt–Ru Cluster Complexes

“…In the past decade these transition metal complexes bearing NHCs were extensively investigated in many important reactions, such as olefin metathesis [5][6][7], Pd-catalyzed cross-coupling reactions [8][9][10][11], and hydrogenation reactions [12][13][14]. More recently focus has been on the activation of small molecules using electronically unsaturated TM-NHC complexes (TM = Ir, Rh, Pd, Ni) [15][16][17]. The ever increasing applications of the NHCs as supporting ligands in catalysis are attributed to their electronic properties and steric variability.…”