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.

Asymmetric Construction of α,γ-Disubstituted α,β-Butenolides Directly from Allylic Ynoates Using a Chiral Bifunctional Phosphine Ligand Enables Cooperative Au Catalysis

A highly efficient construction of chiral γ-substituted α-allyl-α,β-butenolides with up to >99% enantiomeric excess from readily available allylic ynoates is realized. In this asymmetric gold catalysis, the cationic gold(I) catalyst featuring a bifunctional phosphine ligand enables a four-step cascade which permits the conversion of a diverse array of allylic ynoates into valuable chiral α,γ-disubstituted α,β-butenolides.

Stabilizing a 20-Electron Metallaazulyne by Aromaticity

The 18-electron rule states that metal complexes with 18 valence electron metal centers are thermodynamically stable because nine valence orbitals of transition metals including one s orbital, three p orbitals, and five d orbitals can collectively accommodate 18 electrons, achieving the same electron configuration as the noble gas in the period. Thus, 20-electron compounds are extremely rare due to a violation of such a rule.

Predicting Dinitrogen Activation by Carborane-Based Frustrated Lewis Pairs

Activation of atmospherically abundant dinitrogen (N2) under mild conditions has been a great challenge in chemistry for decades because of the significantly strong N≡N triple bond. The traditional strategy of N2 activation was mainly limited to metallic species until the ground-breaking achievement of N2 activation by two-coordinated borylenes was achieved experimentally in 2018. On the other hand, carborane derivatives have attracted considerable interest for small-molecule activation. Still, the utilization of carborane derivatives in N2 activation remains elusive.

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.

Electrochemical Migratory Cyclization of N-acylsulfonamides

Benzoxathiazine dioxide, as a bioisostere of the clinically widely used diazoxide, exhibits interesting biological activity. However, limited success has been achieved in terms of its concise and direct synthesis. We report herein a facile electrochemical migratory cyclization of N -acylsulfonamides to access a diverse array of benzoxathiazine dioxides. The inclusion of electrochemistry is crucial for realizing such a novel transformation, which is substantiated both by the experiments and density-functional-theory calculations.

Unexpected White Phosphorus (P4) Activation Modes with Silylene-Substituted o-Carboranes and Access to an Isolable 1,3-Diphospha-2,4-disilabutadiene

New types of metal-free white phosphorus (P4) activation are reported. While the phosphine-silylene-substituted dicarborane 1, CB-SiP {CB = ortho-C,C´-C2B10H10, Si = PhC(tBuN)2Si, P = P[N(tBu)CH2]2}, activates white phosphorus in a 2:1 molar ratio to yield the P5-chain containing species 2, the analogous bis(silylene)-substituted compound 3, CB-Si2, reacts with P4 in the molar ratio of 2:1 to furnish the first isolable 1,3-diphospha-2,4-disilabutadiene (Si=P-Si=P-containing) compound 4.

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.

Structure, Bonding and Adaptive Aromaticity in Rhenium-oxo Complexes: A DFT Study

In general, species could be aromatic in the ground or excited state only according to Hückel’s and Baird’s rules. Thus, adaptive aromatics are particularly rare as they can be aromatic in both the lowest singlet and triplet states (S0 and T1). Here, we carry out density functional theory calculations on a series of rhenium oxo complexes to examine their structure, bonding, and aromaticity. It is found that all these complexes are aromatic in the S0 state. In contrast, their T1 states could be antiaromatic, nonaromatic, or aromatic depending on the ligands.

Phosphine-Stabilized Germylidenylpnictinidenes as Synthetic Equivalents of Heavier Nitrile and Isocyanide in Cycloaddition Reactions with Alkynes

The reactions of chlorogermylene MsFluindtBu-GeCl 1, supported by a sterically encumbered hydrindacene ligand MsFluindtBu, with NaPCO(dioxane)2.5 and NaAsCO(18-c-6) in the presence of trimethylphosphine afforded trimethylphosphine-stabilized germylidenyl-phosphinidene 2 and -arsinidene 3, respectively. Structural and computational investigations reveal that the Ge–E′ bond (E′ = P and As) features a multiple-bond character.