Cathleen M. Crudden

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

Abstract The metal‐catalyzed hydroboration reaction provides access to functionalized organoboron derivatives that cannot be easily prepared using traditional reagents. New developments in this reaction including neoteric reaction media and novel ligands are described in this review. A key aspect of the hydroboration reaction is the ability to further derivatize the product. Thus the conversion of boronate esters into amines, esters, alcohols, carboxylic acids and amino acids is described. (© Wi

The functionalization of SBA-15 with mercaptopropyl trimethoxysilane leads to a material capable of absorbing Pd from organic and aqueous solutions. The resulting Pd-loaded material acts as a catalyst for the Suzuki-Miyaura and Mizoroki-Heck coupling reactions. Leaching studies show that the filtrate contains as little as 3 ppb Pd after reaction. Aminopropylated silica is an effective scavenger, and catalyst for the Mizoroki-Heck reaction, but leaching is significant (35 ppm), illustrating the i

Gold superatom nanoclusters stabilized entirely by N-heterocyclic carbenes (NHCs) and halides are reported. The reduction of well-defined NHC-Au-Cl complexes produces clusters comprised of an icosahedral Au₁₃ core surrounded by a symmetrical arrangement of nine NHCs and three chlorides. X-ray crystallography shows that the clusters are characterized by multiple CH-π and π-π interactions, which rigidify the ligand and likely contribute to the exceptionally high photoluminescent quantum

The formation of organic films on gold employing N-heterocyclic carbenes (NHCs) has been previously shown to be a useful strategy for generating stable organic films. However, NHCs or NHC precursors typically require inert atmosphere and harsh conditions for their generation and use. Herein we describe the use of benzimidazolium hydrogen carbonates as bench stable solid precursors for the preparation of NHC films in solution or by vapour-phase deposition from the solid state. The ability to prep

The catalyzed hydroboration of vinyl arenes was carried out using pinacol borane instead of catechol borane, as the former reagent and the product boronates are significantly easier to handle. By careful choice of catalyst, either the branched or the linear product can be obtained in greater than 96% selectivity. Interestingly, common ligands such as BINAP and Josiphos give opposite asymmetric induction with pinacol borane as compared with catechol borane, while P,N-ligands such as Quinap gave t

Atomically precise hydrido gold nanoclusters are extremely rare but interesting due to their potential applications in catalysis. By optimization of molecular precursors, we have prepared an unprecedented N-heterocyclic carbene-stabilized hydrido gold nanocluster, [Au₂₄(NHC)₁₄Cl₂H₃]³⁺. This cluster comprises a dimer of two Au₁₂ kernels, each adopting an icosahedral shape with one missing vertex. The two kernels are joined through

The use of boron chemistry for the synthesis of enantiomerically enriched organic compounds is described. Key advances towards the preparation of organoboranes with control of stereochemistry are supplemented by a discussion of the use of these chiral organoboranes in carbon-carbon bond forming reactions. Particular emphasis is given to advances in the Suzuki-Miyaura coupling of chiral secondary organoboranes and homologation reactions. Both of these reactions convert the initially generated B-C

1,2,3-Triazolylidene-based mesoionic carbene boranes have been synthesized in a convenient one-pot protocol from the corresponding 1,2,3-triazolium salts, base, and borane. Borenium ions are obtained by hydride abstraction and serve as catalysts in mild hydrogenation reactions of imines and unsaturated N-heterocycles at ambient pressure and temperature.

NHC-Au^I complexes were used to prepare stable, water-soluble, NHC-protected gold nanoparticles. The water-soluble, charged nature of the nanoparticles permitted analysis by polyacrylamide gel electrophoresis (PAGE), which showed that the nanoparticles were highly monodisperse, with tunable core diameters between 2.0 and 3.3 nm depending on the synthesis conditions. Temporal, thermal, and chemical stability of the nanoparticles were determined to be high. Treatment with thiols caused e

The organometallic chemistry of N-heterocyclic carbene complexes of the transition metals has received significant attention over the past ten years, especially with respect to complexes of Pd and Ru. The present Perspective highlights the chemistry of NHC complexes of another important transition metal, Rh. The application of Rh-NHC complexes in the industrially significant reactions of hydrogenation and hydroformylation is described. In order to accurately assess the activity of these complexe

The Suzuki-Miyaura cross-coupling is one of the most often utilized reactions in the synthesis of pharmaceutical compounds and conjugated materials. In its most common form, the reaction joins two sp(2)-functionalized carbon atoms to make a biaryl or diene/polyene unit. These substructures are widely found in natural products and small molecules and thus the Suzuki-Miyaura cross-coupling has been proposed as the key reaction for the automated assembly of such molecules, using protecting group ch

An original­ syn: The first enantioselective Suzuki–Miyaura cross-coupling of chiral, enantioenriched secondary allylic boronic esters is described (see scheme; DME=dimethoxyethane, Bpin = pinacolboryl, dba = dibenzylideneacetone). Mechanistic studies show that the reactions proceed via γ-selective transmetalation followed by reductive elimination. The reaction provides the first independent confirmation that the transmetalation of boronic esters proceeds via a syn pathway.