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N-Heterocyclic carbenes (NHCs) have become one of the most widely studied class of ligands in molecular chemistry and have found applications in fields as varied as catalysis, the stabilization of reactive molecular fragments, and biochemistry. More recently, NHCs have found applications in materials chemistry and have allowed for the functionalization of surfaces, polymers, nanoparticles, and discrete, well-defined clusters. In this review, we provide an in-depth look at recent advances in the use of NHCs for the development of functional materials.

We present isolable examples of formal zinc hydride cations supported by N-heterocyclic carbene (NHC) donors, and investigate the dual electrophilic and nucleophilic (hydridic) character of the encapsulated [ZnH](+) units by computational methods and preliminary hydrosilylation catalysis.

Herein, we describe the synthesis of a toroidal Au 10 cluster stabilized by N -heterocyclic carbene and halide ligands via reduction of the corresponding NHC–Au–X complexes (X = Cl, Br, I). The significant effect of the halide ligands on the formation, stability, and further conversions of these clusters is presented. While solutions of the chloride derivatives of Au 10 show no change even upon heating, the bromide derivative readily undergoes conversion to form a biicosahedral Au 25 cluster at room temperature. For the iodide derivative, the formation of a significant amount of Au 25 was observed even upon the reduction of NHC–Au–I. The isolated bromide derivative of the Au 25 cluster displays a relatively high ( ca . 15%) photoluminescence quantum yield, attributed to the high rigidity of the cluster, which is enforced by multiple CH−π interactions within the molecular structure. Density functional theory computations are used to characterize the electronic structure and optical absorption of the Au 10 cluster. 13 C-Labeling is employed to assist with characterization of the products and to observe their conversions by NMR spectroscopy.

The extremely bulky N-heterocyclic carbene (NHC), ITr (ITr=[(HCNCPh ) C:]) featuring sterically shielding umbrella-shaped trityl (CPh ) substituents was prepared. This NHC features the highest percent buried volume (%V ) to date, and was used to form a thermally stable quasi one-coordinate thallium(I) cation [ITr-Tl] . This Tl adduct and the corresponding lithium complex [ITr⋅Li(OEt )] are versatile "all-in-one" transmetalation/ligation reagents for preparing low-coordinate inorganic species inaccessible by pre-existing routes.

Benzimidazolium hydrogen carbonate salts have been shown to act as N‐heterocyclic carbene precursors, which can remove oxide from copper oxide surfaces and functionalize the resulting metallic surfaces in a single pot. Both the surfaces and the etching products were fully characterized by spectroscopic methods. Analysis of surfaces before and after NHC treatment by X‐ray photoelectron spectroscopy demonstrates the complete removal of copper(II) oxide. By using 13C‐labelling, we determined that the products of this transformation include a cyclic urea, a ring‐opened formamide and a bis‐carbene copper(I) complex. These results illustrate the potential of NHCs to functionalize a much broader class of metals, including those prone to oxidation, greatly facilitating the preparation of NHC‐based films on metals other than gold.

The preparation of a novel Au6 cluster bearing a bidentate mixed carbene–thiolate ligand is presented.

The synthesis and coordination chemistry of a series of dianionic bis(amido)silyl and bis(amido)disilyl, [NSiN] and [NSiSiN], chelates with N-bound aryl or sterically modified triarylsilyl (SiAr(3)) groups is reported. In order to provide a consistent comparison of the steric coverage afforded by each ligand construct, various two-coordinate N-heterocyclic germylene complexes featuring each ligand set were prepared and oxidative S-atom transfer chemistry was explored. In the cases where clean oxidation transpired, sulfido-bridged centrosymmetric germanium(IV) dimers of the general form [LGe(μ-S)](2) (L = bis(amidosilyl) ligands) were obtained in lieu of the target monomeric germanethiones with discrete Ge═S double bonds. These results indicate that the reported chelates possess sufficient conformational flexibility to allow for the dimerization of LGe═S units to occur. Notably, the new triarylsilyl groups (4-RC(6)H(4))(3)Si- (R = (t)Bu and (i)Pr) still offer considerably expanded degrees of steric coverage relative to the parent congener, -SiPh(3,) and thus the use of substituted triarylsilyl groups within ligand design strategies should be a generally useful concept in advancing low-coordination main group and transition-metal chemistry.