Simple carbenes as hydrogen bond acceptors: determination of nucleophilicities and reduced nucleophilicities.

Nucleophilicities for a range of simple carbene molecules acting as hydrogen bond acceptors B in forming complexes B⋯HX are reported. The carbenes chosen to fulfil the roles of a Lewis base are B = RM, -(CH)M, HCCM and two N-heterocyclic carbenes, where M is one of the group 14 tetrel atoms, C, Si, Ge or Sn and R = H, CH, and F. All the carbenes but CH have a singlet electronic ground state.

Computational design for enantioselective CO capture: asymmetric frustrated Lewis pairs in epoxide transformations.

Carbon capture and utilisation (CCU) technologies offer a compelling strategy to mitigate rising atmospheric carbon dioxide levels. Despite extensive research on the CO insertion into epoxides to form cyclic carbonates, the stereochemical implications of this reaction have been largely overlooked, despite the prevalence of racemic epoxide solutions. This study introduces an in silico approach to design asymmetric frustrated Lewis pairs (FLPs) aimed at controlling reaction stereochemistry.

Hydride and halide abstraction reactions behind the enhanced basicity of Be and Mg clusters with nitrogen bases.

In this study, we investigate the protonation effects on the structure, relative stability and basicity of complexes formed by the interaction of monomers and dimers of BeX and MgX (X = H, F) with NH, CHNH, HCN, and NCH bases. Calculations were performed using the M06-2X/aug-cc-pVTZ formalism, along with QTAIM, ELF and NCI methods for electron density analysis and MBIE and LMO-EDA energy decomposition analyses for interaction enthalpies. The protonation of the MH- and MH-Base complexes occurs at the negatively charged hydrogen atoms of the MH and MH moieties through typical hydride abstraction reactions, while protonation at the N atom of the base is systematically less exothermic.

Investigation of Tetrel Bonds in Isolated Complexes Formed Between a Lewis Acid HMX, M-O or M-S (M = Si, Ge, or Sn) and the Lewis Bases B = N, CO, HCCH, PH, CH, HCN, CS, HNC, NP, HO, and NH.

Isolated complexes of the type B⋯A in which the noncovalent interaction is a tetrel bond have been characterized by calculations at the CCSD(T)(F12c)/cc-pVDZ-F12 level. The Lewis bases B involved were N, CO, HCCH, PH, CH, HCN, CS, HNC, NP, HO and NH. Two types of Lewis acid A were examined, each containing one of the tetrel atoms M = Si, Ge or Sn, The Lewis acids in the first series were the HMX (X = F, Cl, CN, H), in each of which the most electrophilic region was found to lie on the axis of the C molecules, near to the tetrel atom M.