Unveiling the True Identity of Carborane-Fused Phosphorus Heterocycles

In recent years, the possible global 2D/3D aromaticity of carborane-fused cycles has been widely debated. While phosphorus heterocycles fused with carboranes are known, the 2D aromatic character in carborane-fused phospholes was only recently reported. However, our computational study found that these compounds lack 2D aromaticity. Instead, they should be viewed not as a fusion of an aromatic ring but as a fusion of an unsaturated ring with carboranes.