Density functional theory (DFT) calculations reveal that for ligand directed aromatic ring C-H bond activation, the agostic donation can share the same antibonding acceptor orbitals as a previously unrecognised π-donation from the aromatic ring of the ligand. The recognition of carbon based orbitals assisting the agostic interaction has significant implication for C-H bond activation chemistry.
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http://dx.doi.org/10.1039/c7cc01167a | DOI Listing |
Chemphyschem
January 2025
The University of Sheffield, school of mathematical and physical sciences, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND.
Pentalene (C8H6) and NN- and BB-bridged heterocyclic analogues (BN)4H6, derived by replacement of CC pairs with BN, are taken as paradigms for tuning of ring-current (anti)aromaticity by variation of π charge, electronegativity and substitution pattern. Ab initio calculation of maps for the π current density induced in these model systems by a perpendicular external magnetic field exhibits the full range of tropicity, from diatropic aromatic to nonaromatic to paratropic antiaromatic, with a ready rationalisation in terms of an orbital model. Further calculations on systems of varying charge in which these motifs are embedded in extended PAH systems with naphthalene and phenanthrene 'clamps' show promise for switching between current patterns and related opto-electronic properties.
View Article and Find Full Text PDFChem Asian J
January 2025
Xiamen University, Department of Chemistry, Xiamen University, Lujiaxi Building Room 742, 361005, xiamen, CHINA.
The direct construction of polycyclic arenes through ring formation using simple building blocks is highly appealing but remains challenging in organic chemistry. In this study, we introduce an efficient cascade reaction that combines dearomatizing photocyclization with oxidative aromatization, driven by organophotocatalysis. Conducted under mild, transition-metal-free conditions, this reaction seamlessly converts styrene derivatives into a diverse array of functionalized polycyclic aromatic compounds with good yields and regioselectivity.
View Article and Find Full Text PDFOrg Biomol Chem
January 2025
Department of Applied Chemistry, Waseda University, 513 Wasedatsurumakicho, Shinjuku, Tokyo 162-0041, Japan.
Nitroarenes are highly versatile building blocks in organic synthesis, playing a pivotal role in various reactions. Common transformations involving nitroarenes include nucleophilic aromatic substitution (SAr) reactions, where the nitro group functions both as a potent electron-withdrawing group that activates the aromatic ring and as a leaving group facilitating the substitution. Additionally, the direct transformation of nitro groups, such as reduction-driven syntheses of amines and carboxylic acids, as well as -substitution SAr reactions, have been extensively explored.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States.
Under most conditions, 2,4-dihalopyrimidines undergo substitution reactions at C4. Here we report that Pd(II) precatalysts supported by bulky -heterocyclic carbene ligands uniquely effect C2-selective cross-coupling of 2,4-dichloropyrimidine with thiols. The regioselectivity of this reaction stands in stark contrast to ∼1500 previously reported Pd-catalyzed cross-couplings that favor C4 in the absence of other substituents on the pyrimidine ring.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Chinese Academy of Sciences Fujian Institute of Research on the Structure of Matter, Key Laboratory of Structural Chemistry, CHINA.
One-step adsorptive purification of ethylene (C2H4) from ternary mixture comprising of acetylene (C2H2), ethylene (C2H4) and carbon dioxide (CO2) is a great challenge in the chemical industry. Herein, a microporous metal-organic framework (FJI-H38) has been reported, which possesses a high density of electronegative O/N binding sites and appropriate pore size. Notably, at 0.
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