Res. Chem. Int. Volume 49, pages 3205–3225, (2023)

https://link.springer.com/article/10.1007/s11164-023-05031-5

Abstract

During this study, six carbenes, consisted of various substitutions (hydrogen, deuterium, fluorine, chlorine, bromine, and methyl) and their 24 related carbenoids (using Li, Na, Be, and Mg metals) were designed. These species were theoretically studied to obtain the extensive and comprehensive information about their structures, stabilities, atomic specifications, and bonding properties using MP2/aug-cc-pVTZ level of theory. Moreover, the PBE1PBE DFT method was used for IQA analyses using AIMAll program package. The calculated molecular parameters showed that the electronegativity and the size of ligand are effective on the studied structures. Moreover, the electronegativity effect is more important than the size. Atomic hybridizations results showed the p indexes of carbon in triplet carbenes are also smaller than those in singlet carbenes, but this difference in halogen-containing carbenes is smaller than the other carbenes. In population analyses, except for sodium-based carbenoids, all carbenoids have higher Eg values than the carbenes. The ΔG values for α-elimination reaction, as a method of preparation of these carbenes, were obtained in order of f < c < b < m < h, which is reversely related to the electronegativities of the connected ligands. IQA analyses were performed to evaluate the relative stability of carbenes. It was found that the classical interaction in C–F is attractive (negative) unlike the other mentioned bonds energy for carbenes. This electrostatic term in C–F is larger in the singlet state than the triplet state, which leads to the singlet state of CF₂ being more stable and consequently more favorable than its triplet state.