N-Heterocyclic carbenes have become universal ligands in organometallic and inorganic coordination chemistry. They not only bind to any transition metal, be it in low or high oxidation states, but also to main group elements such as beryllium, sulfur, and iodine. Because of their specific coordination chemistry, N-heterocyclic carbenes both stabilize and activate metal centers in quite different key catalytic steps of organic syntheses, for example, C-H activation, C-C, C-H, C-O, and C-N bond formation. There is now ample evidence that in the new generation of organometallic catalysts the established ligand class of organophosphanes will be supplemented and, in part, replaced by N-heterocyclic carbenes. Over the past few years, this chemistry has been the field of vivid scientific competition, and yielded previously unexpected successes in key areas of homogeneous catalysis. From the work in numerous academic laboratories and in industry, a revolutionary turning point in oraganometallic catalysis is emerging.

http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/NHC-%20liganden%20Herrmann.pdf

N-heterocyclic carbenes: a new concept in organometallic catalysis.

The chemistry of heterocyclic carbenes has experienced a rapid development over the last years. In addition to the imidazolin-2-ylidenes, a large number of cyclic diaminocarbenes with different ring sizes have been described. Aside from diaminocarbenes, P-heterocyclic carbenes, and derivatives with only one, or even no heteroatom within the carbene ring are known. New methods for the synthesis of complexes with N-heterocyclic carbene ligands such as the oxidative addition or the metal atom template controlled cyclization of β-functionalized isocyanides have been developed recently. This review summarizes the new developments regarding the synthesis of N-heterocyclic carbenes and their metal complexes.

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

The fascinating story of olefin (or alkene) metathesis (eq
1) began almost five decades ago, when Anderson and
Merckling reported the first carbon-carbon double-bond
rearrangement reaction in the titanium-catalyzed polymerization of norbornene. Nine years later, Banks and Bailey reported “a new disproportionation reaction . . . in which olefins are converted to homologues of shorter and longer carbon chains...”. In 1967, Calderon and co-workers named this metal-catalyzed redistribution of carbon-carbon double bonds olefin metathesis, from the Greek word “μeτάθeση”, which means change of position. These contributions have since served as the foundation for an amazing research field, and olefin metathesis currently represents a powerful transformation in chemical synthesis, attracting a vast amount of interest both in industry and academia.

https://core.ac.uk/download/pdf/4884240.pdf

Ruthenium-based heterocyclic carbene-coordinated olefin metathesis catalysts.

Palladium-catalyzed C-C and C-N bond-forming reactions are among the most versatile and powerful synthetic methods. For the last 15 years, N-heterocyclic carbenes (NHCs) have enjoyed increasing popularity as ligands in Pd-mediated cross-coupling and related transformations because of their superior performance compared to the more traditional tertiary phosphanes. The strong sigma-electron-donating ability of NHCs renders oxidative insertion even in challenging substrates facile, while their steric bulk and particular topology is responsible for fast reductive elimination. The strong Pd-NHC bonds contribute to the high stability of the active species, even at low ligand/Pd ratios and high temperatures. With a number of commercially available, stable, user-friendly, and powerful NHC-Pd precatalysts, the goal of a universal cross-coupling catalyst is within reach. This Review discusses the basics of Pd-NHC chemistry to understand the peculiarities of these catalysts and then gives a critical discussion on their application in C-C and C-N cross-coupling as well as carbopalladation reactions.

Palladium Complexes of N-Heterocyclic Carbenes as Catalysts for Cross-Coupling Reactions—A Synthetic Chemist's Perspective

Organocatalytic Reactions Enabled by N-Heterocyclic Carbenes.

Imidazolylidenes, imidazolinylidenes and imidazolidines

Syntheses, Structural Characterization, and First Electroluminescent Properties of Mono-cyclometalated Platinum(II) Complexes with Greater than Classical π−π Stacking and Pt−Pt Distances†

Disclosed are solid forms of 8-chloro-N-[(2-chloro-5-methoxyphenyl)sulfonyl]-6-(trifluoromethyl)-imidazo[1,2-a]pyridine-2-carboxamide (Compound 1). Methods for the preparation of solid forms of Compound 1 and for the conversion of one solid form of Compound 1 into another are disclosed. Disclosed are nematocidal compositions comprising a nematocidally effective amount of a solid form of Compound 1 and at least one additional component selected from the group consisting of surfactants, solid diluents and liquid carriers. Compositions comprising a mixture of a solid form of Compound 1 and at least one other nematicide, insecticide and/or fungicide are also disclosed. Also disclosed are methods for protecting a plant from nematodes comprising applying to the plant, or portion, or seed thereof, or to the growing medium of the plant, a nematocidally effective amount of Compound 1 comprising the polymorph Form A.

Solid forms of nematocidal sulfonamides

ortho-5-Methylfuran- and Benzofuran-Substituted η3-Allyl(α-diimine)nickel(II) Complexes: Syntheses, Structural Characterization, and the First Polymerization Results†

High-temperature catalysts for the production of α-olefins based on Iron(II) and Iron(III) tridentate Bis(imino)pyridine complexes with double pattern of substitution : ortho-methyl plus meta-aryl

William J. Marshall

Papers

Imidazolylidenes, imidazolinylidenes and imidazolidines

Syntheses, Structural Characterization, and First Electroluminescent Properties of Mono-cyclometalated Platinum(II) Complexes with Greater than Classical π−π Stacking and Pt−Pt Distances†

Solid forms of nematocidal sulfonamides

ortho-5-Methylfuran- and Benzofuran-Substituted η3-Allyl(α-diimine)nickel(II) Complexes: Syntheses, Structural Characterization, and the First Polymerization Results†

High-temperature catalysts for the production of α-olefins based on Iron(II) and Iron(III) tridentate Bis(imino)pyridine complexes with double pattern of substitution : ortho-methyl plus meta-aryl