Oxidative Coupling Reaction of Methane

The NH Functional Group in Organometallic Catalysis

“…In 2008, Ikariya and co‐workers reported an efficient hydrogenation of lactones by using Ru complex 139 as catalyst, affording various diols in good yields (Scheme ) 2ai. 88 Ligand effect was investigated for the reaction, and the ligand without NH end was found to be ineffective for the lactone hydrogenolysis (Scheme ) 88b.…”

“…Although many successful applications of NH functions in organometallic catalysis have been achieved, reviews on this chemistry are still very limited. Noyori,2d,f–h,l, m,r Ikariya,2t–v,z,aa,ag,ai Andersson and Bäckvall,2s and others2p,y,ae have contributed several excellent reviews on MNH bifunctional catalysis recently; however, a thorough review including diverse aspects of NH functions in organometallic catalysis have not been reported to date. Based on this situation, we try to include, classify, and summarize the main aspects of N‐H functions in organometallic catalysis in this Review, and we try to provide an overview of this chemistry and provide useful perspectives for future development of this exciting area.…”

Unsymmetrical Pincer‐Type Ruthenium Complex Containing β‐Protic Pyrazole and N‐Heterocyclic Carbene Arms: Comparison of Brønsted Acidity of NH Groups in Second Coordination Sphere

“…Proton‐responsive ligands surrounding a metal play crucial roles in metal–ligand bifunctional catalysis 1. A variety of protic ligands, such as amines,2, 3 pyrazoles,4–9 imidazoles,10 oximes,11, 12 pyridinols,13 and picoline/lutidine‐based chelates,14 have been used to facilitate the substrate binding, activation, and transformation through noncovalent interactions. Although most of the artificial bifunctional catalysts have only one kind of such protic ligands, metalloenzymes in Nature generally possess two or more structurally differentiated cooperating groups with various ranges of proton affinity in the second coordination sphere, which accelerate biological transformations in a delicate manner 15.…”

“…Although most of the artificial bifunctional catalysts have only one kind of such protic ligands, metalloenzymes in Nature generally possess two or more structurally differentiated cooperating groups with various ranges of proton affinity in the second coordination sphere, which accelerate biological transformations in a delicate manner 15. During our continuing study on the metal–ligand bifunctional catalysts,3–7, 16, 17 we have recently synthesized a symmetrical pincer‐type ruthenium complex 1 featuring two protic pyrazole arms,5 and also demonstrated that its iron analogue catalyzes disproportionation of hydrazine through bidirectional, two‐proton‐coupled two‐electron transfer 6. Differentiation of the cooperating protic sites would be beneficial to more efficient substrate recognition, proton transfer, and stabilization of the reaction intermediates.…”

Toward a Symphony of Reactivity: Cascades Involving Catalysis and Sigmatropic Rearrangements

“…The classification herein is in contrast to “concerto catalysis,” which seeks to improve traditional metallic catalysts by uniting them with all scales of catalytic assemblies, from large biological macromolecules to small molecules, an endeavor which would require and encourage cross-disciplinary thinking. [2] Both concepts appeal to the musical sense of orchestration in chemical synthesis, and illustrate the goal of chemists to attain more exquisite control over chemical processes.…”