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The performance of density functionals and wavefunction methods for describing the thermodynamics and kinetics of hydride reductions of 2‐substituted cyclohexanones has been evaluated for the first time. A variety of exchange correlation functionals ranging from generalized gradient approximations to double hybrids have been tested and their performance to describe the facial selectivity of hydride reductions of cyclohexanones has been carefully assessed relative to the CCSD(T) method. Among the tested methods, an approach in which single‐point energy calculations using the double hybrid B2PLYP−D3 functional on ωB97X−D optimized geometries provides the most accurate transition state energies for these kinetically‐controlled reactions. Moreover, the role of torsional strain, temperature, solvation, noncovalent interactions on the stereoselectivity of these reductions was elucidated. Our results indicate a prominent role of the substituent on the cis/trans ratios driven by the delicate interplay between torsional strain and dispersion interactions. [ABSTRACT FROM AUTHOR]

The importance of axially chiral biaryls has risen steeply in the recent decades. This structural motif proved to be successful in catalytic asymmetric synthesis and the configuration of the biaryl axis is decisive for the biological activity. A new approach for the atroposelective synthesis of biaryls would be through a cycloaddition between an enantiopure phenyl‐substituted thiophene S‐oxide and an alkyne. Importantly, the chiral center of the thiophene S‐oxide needs to be stable enough to avoid pyramidal inversion during the cycloaddition. Considering that the racemization of thiophene monoxides has been scarcely investigated so far, we perform a thorough quantum chemical study on the inversion barriers of a large number of chiral thiophene S‐oxide derivatives. Our main goal is to identify substitution patterns leading to stable atropisomers at room temperature. Appealingly, the role of stereoelectronic effects and the position of the substituents as well as the importance of aromaticity on the pyramidal inversion barrier are elucidated for the first time. Hindering pyramidal inversion: A detailed quantum chemical investigation revealed substitution patterns that provide stable chiral thiophene monoxides, which enabled a novel atroposelective synthesis of biaryl compounds through a center‐to‐axis chirality transfer. Aromaticity variations emerge as a guiding principle to rationalize the pyramidal inversion barriers of a large set of thiophene S‐oxides. [ABSTRACT FROM AUTHOR]

The heretofore unpredictable behavior of [26] and [28]hexaphyrins upon metalation has been elucidated through quantum chemical calculations. It is demonstrated that the molecular topology of Group 10 and Group 11 metal complexes of hexaphyrins depends on sensitive interplay between the intrinsic ligand strain and the metal-ligand interaction strength. As such, the aromaticity of the ligand and effective charge of the metal are revealed as key factors determining the binding mode and the preference for Möbius or Hückel structures. These findings offer a new perspective to rationalize experimental observations for metalated hexaphyrins. More importantly, the proposed guidelines could be useful for designing novel complexes of hexaphyrins, such as a hitherto unknown Möbius [26]hexaphyrin complex. [ABSTRACT FROM AUTHOR]

Invited for this month's cover is the Quantum Chemistry group (ALGC) of the Free University of Brussels (VUB) in collaboration with the Molecular Design and Synthesis (MolDesignS) group of the KU Leuven. The image shows how a variety of computational techniques, such as density functional theory, molecular dynamics, and the noncovalent interaction index, can be used to virtually zoom in on the noncovalent interactions that are key for the supramolecular hydrogelation of bis‐urea‐based gelators. Read the full text of the article at 10.1002/cplu.201900551. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue is the ALGC Quantum Chemistry group of the Free University of Brussels (VUB) in collaboration with the LCT group in Paris. The image depicts how π/π and σ/σ stacking interactions are surprisingly equal in strength for the benzene and cyclohexane dimers, but different in origin, and how π-stacking becomes more important as the size of the dimer increases. Read the full text of the article at . [ABSTRACT FROM AUTHOR]