Halogen bonds with carbenes acting as Lewis base units: complexes of imidazol-2-ylidene: theoretical analysis and experimental evidence
Sławomir J. Grabowski
Abstract
units were chosen here as those that interact through the X Lewis acid halogen centre (X = Cl, Br and I); if X = F the complexes are linked by interactions which are not classified as halogen bonds. The properties of interactions that occur in complexes are analyzed using the results of DFT calculations which are supported by parameters derived from the Quantum Theory of Atoms in Molecules, QTAIM, and the Natural Bond Orbital, NBO, approaches. The energy decomposition analysis, EDA, applied here provided additional characteristics of interactions linking complexes analyzed. The majority of complexes are linked by the medium in strength and strong halogen bonds which often possess characteristics typical for covalent bonds. Searches through the Cambridge Structural Database were also performed and structures analogues to complexes analyzed theoretically were found, and these structures are also discussed in this study.