Atom Swapping Reaction on Diborylcarbenoid: Synthesis and Electronic Structure of Inorganic Chalcogenophene Analogues

ABSTRACT Inorganic analogues of aromatic compounds, wherein C═C bonds are replaced with B─N bonds, are isoelectronic with the original aromatic compounds, however, they can show different properties. While borazine, an inorganic analogue of benzene, has been well‐studied, inorganic analogues of chalcogenophene have been less explored. Here, we synthesized crystalline isolable inorganic furan 2 O and thiophene 2 S by atom swapping reaction at the carbenoid carbon of K/Cl‐diborylcarbenoid, an equivalent to diborylcarbene. Density functional theory calculation exhibited that, in contrast to the quite weak aromatic character of borazine, inorganic chalcogenophenes 2 O and 2 S have a moderate aromaticity. Theoretical investigation of the reaction mechanism suggested that the atom swapping reaction occurred via oxidation of diborylcarbenoid 1 to diboralactone intermediate 3 Ch and the following intramolecular rearrangement reaction.