reaction mechanism

Electrochemical cascade migratory versus ortho-cyclization of 2-alkynylbenzenesulfonamides

Efficient control over several possible reaction pathways of free radicals is the chemical basis of their highly selective transformations. Among various competing reaction pathways, sulfonimidyl radicals generated from the electrolysis of 2-alkynylbenzenesulfonamides undergo cascade migratory or ortho-cyclization cyclization selectively.

Probing the Origin of Higher Efficiency of Terphenyl Phosphine over the Biaryl Framework in Pd-catalyzed C-N Coupling: A Combined DFT and Machine Learning Study

The Pd-catalyzed Buchwald–Hartwig coupling reaction is important in the construction of the C-N bond due to various applications in organic synthesis. Quantum chemical calculations are widely used in understanding reaction mechanisms whereas the machine learning method is extremely popular in recognizing the relationships of data. Here, we combine density functional theory calculations with the support vector regression method to probe the origin of the higher efficiency of terphenyl phosphine ligand over the biaryl counterpart in the Buchwald–Hartwig C-N coupling reaction.

The application of aromaticity and antiaromaticity to reaction mechanisms

Aromaticity, in general, can promote a given reaction by stabilizing a transition state or a product via a mobility of π electrons in a cyclic structure. Similarly, such a promotion could be also achieved by destabilizing an antiaromatic reactant. However, both aromaticity and transition states cannot be directly measured in experiment. Thus, computational chemistry has been becoming a key tool to understand the aromaticity-driven reaction mechanisms.

An unprecedented route to achieve persistent 1H-azirine

1H-azirine, a highly reactive, antiaromatic, and unstable tautomer of the aromatic, stable, and (sometimes) isolable 2H-azirine, is stabilized, both thermodynamically and kinetically, via an unprecedented route, where the latter serves as the precursor–exploiting electronic and steric elements. Our density functional theory results invite experimentalists to realize isolable 1H-azirine.

Mechanism of metalated pyrrole-singlet oxygen chemiluminescent reaction

Visible-light-mediated dearomatisation of pyrroles is a powerful strategy for the synthesis of pharmaceuticals and bioactive compounds. Herein we present the chemiluminescent reaction between pyrrole metalated-Ir(III) complex [Ir(K2C,N-DPP)(H)(Cl)(PPh3)2] (1) and singlet oxygen to form a ketoamide complex [Ir(K2C,N-ketoamide)(H)(Cl)(PPh3)2] (2). Complex 2 are fully characterized by NMR and single crystal X-ray diffraction analysis.

Screening Carbon-Boron Frustrated Lewis Pairs for Small-Molecule Activation including N2, O2, CO, CO2, CS2, H2O and CH4: A Computational Study

Dinitrogen (N2) activation is particularly challenging under ambient conditions because of its large highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap (10.8 eV) and high bond dissociation energy (945 kJ mol–1) of the NΞN triple bond, attracting considerable attention from both experimental and theoretical chemists. However, most effort has focused on metallic systems. In contrast, nitrogen activation by frustrated Lewis pairs (FLPs) has been initiated recently via theoretical calculations.

Understanding reaction mechanisms of metal-free dinitrogen activation by methyleneboranes

Dinitrogen activation under mild conditions is important but extremely challenging due to the inert nature of the N-N triple bond evidenced by high bond dissociation energy (945 kJ/mol) and large HOMO-LUMO gap (10.8 eV). In comparison with largely developed transition metal systems, the reported main group species on dinitrogen activation are rare. Here, we carry out density functional theory calculations on methyleneboranes to understand the reaction mechanisms of their dinitrogen activation.

Mechanistic Insight into the Ni-Catalyzed Kumada Cross-Coupling: Alkylmagnesium Halide Promotes C–F Bond Activation and Electron-Deficient Metal Center Slows Down β-H Elimination

The Ni-catalyzed Kumada–Tamao–Corriu (KTC) cross-coupling between aryl fluorides and alkyl Grignard reagents has been used to achieve a highly selective Csp2–Csp3 bond construction via the carbon–fluorine (C–F) bond activation. However, the detailed mechanism of this groundbreaking KTC reaction remains unclear. Herein, we perform a series of analyses by density functional theory (DFT) calculations in order to understand the reaction mechanisms for the selective activation of a highly inert C–F bond by Ni catalysts with bidentate phosphorus ligands.

Predicting Dinitrogen Activation by Borenium and Borinium Cations

Activation of thermodynamically stable and kinetically inert dinitrogen (N2) has been a great challenge due to a significantly strong triple bond. Recently, the experimental study on the N2 activation by boron species, a highly reactive two-coordinated borylene, broke through the limitation of traditional strategy of N2 activation by metal species. Still, the study on metal-free N2 activation remains undeveloped.

Theoretical Study on Reaction Mechanisms of Dinitrogen Activation and Coupling by Carbene-Stabilized Borylenes in Comparison with Intramolecular C-H Bond Activation

Dinitrogen (N2) activation is particularly challenging due to the significantly strong N≡N bond, let alone the catenation of two N2 molecules. Recent experimental study shows that cyclic (alkyl)(amino)carbene (CAAC)-stabilized borylenes are able to tackle N2 activation and coupling below room temperature. Here we carry out density functional theory calculations to explore the corresponding reaction mechanisms. The results indicate that the reaction barrier for the dinitrogen activation by the first borylene is slightly higher than that by the second borylene.