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NHCs as ligands are known for their strong σ donation and high structural tunability. [11] More in-depth computational analyses also highlight the role of M to NHC π back-donation, with respect to a description of an M-NHC bond. [12] Contour line diagrams of the Laplacian distribution of three (NHC)MCl complexes.
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.
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.
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 ...
The transmetallated NHCs can either be isolated for subsequent reaction with palladium in a two-step method, or generated in the presence of palladium in a one-pot reaction. However, generation of Pd-NHC complexes by Ag transmetallation is cost-prohibitive and hampered by Ag complexes’ light sensitivity.
When the alkyl group bridges two main group elements, the bonding is called three-center two-electron bonds. This pattern is seen for dimethyl beryllium and trimethylaluminium. In the case of methyl lithium, the methyl group can be shared (bonded to) three Li centers. These bonding aspects influence the structures: Trimethylaluminium, dimethyl ...
Anionic boryl ligands can covalently bond to transition metals, which is different than how it bonds to main group elements (ionically). [19] These boryl ligands σ-bond but also are able to receive π-back donation into the vacant p z orbital that the boron has. It is said that boryl ligands, like NHC boryl anions, are the most effective ...
Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of organic heterocycles. [2] Examples of heterocyclic compounds include all of the nucleic acids, the majority of drugs, most biomass (cellulose and related materials), and many natural and synthetic dyes. More than half of ...