A textbook case of twisted structure due to hydrogen-hydrogen steric clash, the biphenyl molecule, has been studied in real space from a new perspective. Long-term discrepancies regarding the origin of...

Stable dimers of protonated pyridine–boronic acid are found in the gas phase and solvent models. The importance of electrostatics is discussed.

No abstract

Carbon dioxide can form compounds with nitrogen heterocyclic carbenes (NHCs) based on azoles through noncovalent interactions or by covalent bonding. A narrow dependence on the carbene structure has been observed for the preference for one or the other type of bonding, as revealed by a series of physicochemical descriptors. In our survey, a set of NHCs based on the azole family (three classical, three abnormal, and one remote) was shown to bind CO2 at the accurate G4MP2 computational level. In most cases, exothermic reaction profiles towards the covalently bound form were found, which reached stabilization enthalpies of up to −77 kJ mol−1 for the remote carbene case. Both noncovalent and covalent minima and the corresponding transition state that connects them have been identified as stationary points along the reaction coordinate.