ABSTRACT New indenylidene-type second generation catalysts bearing modified unsymmetrically substituted N-heterocyclic carbene ligands were synthesized. The complexes contain an N-mesityl and N'-nitrobenzyl substituted NHC ligand. The precursors of free carbenes-imidazolinium salts-were obtained in an easy and environment-friendly way (under aqueous or neat conditions). The new catalysts were p...

Theoretical calculations were carried out to understand the effect of annulation on the electronic and ligand properties of boron substituted N-heterocyclic carbenes (B-NHCs). Annulation results in a decrease in stability as indicated by the calculated values of singlet-triplet separations and stabilization energies as well as HOMO-LUMO gaps. Annulated B-NHCs are found to be weaker σ-donors but...

Single-walled boron nitride nanotubes are chosen as model reactants, and (10,0) and (6,6) are chosen as representatives of armchair and zigzag nanotubes, respectively, to study the interaction of carbenes of the type :CX2. It is found that, contrary to the case of carbon nanotubes, boron nitride tubes, particularly armchair BNNTs, do not show a propensity for cyclopropane ring formation. The SW...

HBCBH and HAlCAlH are related electrondeficient molecules, predicted as local minima on their respective potential energy surfaces. Different views of their electronic structure—as allenes, carbenes, or carbones—prompted two research groups to a friendly competition exploring the predilection of these small molecules to dimerize. Many such dimers emerged from the calculations, some with large e...

The unprecedented reaction of trisubstituted alkenes with iron porphyrin carbenes has been successfully developed. Both multiply substituted 1,3-butadiene and cyclopentadiene products are readily accessible with high efficiency and selectivity in good yields.

Conjugate acids of cyclic (amino)(phosphino)carbenes (P-NHCs) have been prepared, and several different processes have been observed during their deprotonation, which include the formation of a metastable P-NHC, an azomethine ylide, and a bicyclic phosphirane.

Gold-catalyzed synthesis of buta-1,3-dien-2-yl esters by the reaction of propargyl esters with vinylazides is described; the reaction mechanism is postulated to involve a vinyl attack of vinylazides at alkenyl gold carbenes.

The controllable synthesis of 3-methylene-2,3-dihydrobenzofurans 2 and 3-methylene-2,3-dihydroindoles 5 has been developed through Rh-catalyzed intramolecular annulation of aromatic rings with azavinyl carbenes.

Thermally-reversible covalent polymers featuring dynamic carbon-carbon double bonds and tunable molecular weights were prepared from difunctional carbenes; addition of transition metal complexes to these materials afforded the respective main-chain organometallic polymers.

It is shown that model oxides grown on metallic substrates catalyze propylene metathesis to form ethylene and butene with an activity that mimics that of supported catalysts for reaction below ∼650 K. Another reaction regime is found for olefin metathesis above ∼650 K, where the reaction proceeds with a much higher activation energy of ∼60 kcal/mol. Unfortunately, alkenes do not react to any de...