Study of pyridyl and phenyl anellated imidazole-2-ylidenes and Si/Ge heavier analogues: structure, stability and aromaticity by DFT method

In this study, the structure, relative stability and aromaticity of structural isomers of imidazole-2-ylidene anodized by phenyl or pyridyl and their heavier Si and Ge companions were examined by DFT method. Also, NBO calculations were performed to obtain important information about a pair of unstable electrons, polarity, the charge on each atom, and the bonding order of the bonds in the molecule, the shapes of the molecular orbitals (HOMO and LUMO). NBO calculations were done on optimized structures using the rB3LYP computational method and in line with the command # POP = NBO (NBO, SAVE NBO) rB3LYP / 6-311 ++ G (3df, 3pd). The energy discrepancy of the HOMO and LUMO orbitals is the perturbation energy of the interaction between the natural giving and receiving orbitals obtained from NBO calculations. Hydrogenated reactions were also examined, as the results confirmed the findings on the energy stability of the optimized structures. NICS calculations were another case to be examined in the aromatic properties of the isomers. Based on the findings friom NICS calculations, N-heterocyclic carbon isomers have more aromatic properties than n-heterocyclic germline and silylene isomers.