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In coordination chemistry, a transition metal NHC complex is a metal complex containing one or more N-heterocyclic carbene ligands. Such compounds are the subject of much research, in part because of prospective applications in homogeneous catalysis. One such success is the second generation Grubbs catalyst. [1] IMes is a popular NHC ligand.
Ever since the first crystalline carbene structure was isolated by Arduengo ins 1990, tuning different properties of NHCs has been a popular area of study in main group chemistry. [4] The first NHC boryl anion was synthesized by Segawa in 2006. [1]
When deprotonated, NHOs can be ligands for main group hydrides. E = Ge, Sn. [1] NHOs can stabilize low oxidation state main group hydrides, like GeH 2 and SnH 2 that are coordinated to W(CO) 5. [1] When deprotonated, these NHOs become anionic, four-electron bridging ligands that can bind to two Ge centers, hence displaying carbanion-like ...
This effect can be used to stabilize highly reactive main group and transition metal compounds. [6] [22] Because excessive steric hindrance can be an issue for some reactivity, NHCs and CAACs bearing substituents with multiple spatial conformations (e.g. cyclohexyl) offer "flexible steric bulk" for catalysis.
Other useful electron-transfer reactions of η 5-C 5 H 5 Fe-η 6-C 6 (CH 3) 6 is the deprotonation of imidazolium salts, generating N-heterocyclic (NHC) carbenes. [12] Arduengo demonstrated that deprotonating these salts produces NHCs that are isolable and relatively stable, provided that the heterocycle nitrogen atoms have appropriate ...
The first mesoionic carbenes based on pyrazole have been reported by Huynh in 2007. [12] These carbenes are referred to as pyrazolin-3(or 4)-ylidenes. Pyrazolin-4-ylidenes are often tetrasubstituted with alkyl or aryl groups; however, the C3 and C5 positions could be substituted with nitrogen- or oxygen-based groups.
A transition metal carbene complex is an organometallic compound featuring a divalent carbon ligand, itself also called a carbene. [1] Carbene complexes have been synthesized from most transition metals and f-block metals, [2] using many different synthetic routes such as nucleophilic addition and alpha-hydrogen abstraction. [1]
He contributed to the field of organocatalysis with a paper published in 2013, wherein he reviewed the roles of N-heterocyclic carbenes (NHCs) in molecular and polymer chemistry, highlighting their electronic properties, synthesis methods, functional group activation, and their application in metal-free polymer synthesis and as structural ...