This short review covers our contribution in the field of the application of group 6 Fischer carbene complexes toward the synthesis of heterocyclic compounds. Alkenyl and alkynyl carbene complexes are suitable partners in [2+2], [3+2], [4+2], and [4+3] cycloaddition reactions. Moreover, chiral alkenyl carbene complexes react in sequential processes involving an initial Michael addition of a ket...

The reactivity and catalytic performance of 2-ethylpyrido[1,2-c][1,2,4]-triazol-3-ylidene 6 have been comprehensively investigated. The carbene 6 has shown unusual properties owing to the effect of the pyrido-annulation. While formohydrazide 8 and hydrazine 9 are obtained via the destruction of the triazole skeleton of the carbene, 3-((1Z,3E)-4-(1H-pyrrol-1-yl)buta-1,3-dienyl)-1-ethyl-1H-1,2,4-...

The potential energy surfaces for the chemical reactions of lattice-framework group 14 heavy carbene species have been studied using density functional theory (B3LYP/LANL2DZ) and the Gibbs free energy method. Five lattice-framework group 14 heavy carbene species, L-F-X: , where X = C, Si, Ge, Sn, and Pb, have been chosen as model reactants in this study. Also, four kinds of chemical reactions, ...

By means of deuterium-labeling experiments, we have carried out a systematic ESI-MS study to determine the mechanism of ESI ionization of alkenyl and alkynyl group 6 Fischer carbene complexes. These compounds can be ionized under ESI conditions only in the presence of additives such as hydroquinone (HQ) or tetrathiafulvalene (TTF). Our results demonstrate that in the ESI source an anion-radical...

Fischer carbene complexes of tungsten with substituents containing up to two additional different transition metals, with all the metals in electronic contact with the carbene carbon atom, were synthesised and studied both in solution and in the solid state. For the complexes of the type [W(CO)(5){C(OR')R}], the substituents chosen were heteroaromatic 2-benzo[b]thienyl (2-BT), or 2-BT π-bonded ...

Diphenyldiazomethane with four iodine groups at the ortho positions and two tert-butyl groups at the para positions, i.e., bis(4-tert-butyl-2,6-diiodophenyl)diazomethane (1a-N₂), was synthesized as a sterically hindered triplet carbene precursor. Irradiation of 1a-N₂ in solution effectively generated the corresponding triplet diphenylcarbene ³1a, which was characterized by UV-vis spectroscopy a...

A series of new piano-stool iron(II) complexes comprising monoand bidentate chelating N-heterocyclic carbene ligands [Fe(cp)(CO)(NHC)(L)]X have been prepared and analyzed by spectroscopic, electrochemical, crystallographic, and theoretical methods. Selectively substituting the L site with a series of ligands going from carbene to pyridine to CO suggests that CO is the strongest π acceptor, whil...

The five-coordinate carbene complexes [Ru{κP,P,Si-Si(Me)(C6H4-2-PiPr2)2}Cl(═CHR)] (2, R = Ph; 3, R = SiMe3), analogues of the Grubbs catalyst, were prepared from the dimer [Ru(μ-Cl){κP,P,Si-Si(Me)(C6H4-2-PiPr2)2}]2 (1) and the corresponding diazoalkane N2CHR. The particular structural features that result from the presence of a strongly trans directing silyl group at the pincer ligand of these ...

The possibility of carbon atom tunneling at cryogenic temperatures for carbene-based ring expansion of adamantane analogues calls for a delicate balance of reactivity to experimentally detect the transpiring reaction. An overly reactive carbene will precipitously decay; an excessively stable carbene will not tunnel. Nevertheless, the factors that affect the quantum-mechanical tunneling (QMT) re...