Are Hetero‐metallapentalenes Aromatic or Not? A DFT Investigation
Aromaticity is one of the most basic concepts in organic chemistry. The planar Möbius aromatic metallapentalynes and metallapentalenes have been attracted considerable attention in the past few years. However, the aromaticity of metallapentalenes containing heteroatoms (such as B, N, and O), termed as hetero‐metallapentalenes, is rarely studied. Here, we theoretically investigated the stability and aromaticity of a series of hetero‐metallapentalenes. The results reveal lower aromaticity in metallaborapentalene, comparable aromaticity in metallazapentalene and non‐aromaticity in metalloxapentalene in comparison with metallapentalene. Moreover, the effect of Lewis bases on the aromaticity and stability of metallaborapentalene is discussed. These results provide useful information for experimental chemists to realize more hetero‐metallapentalenes.