Structures and aromaticity of closo-BnHn−1CO− (n = 5-12)

Closo-BnHn−1CO− (n = 5-12), isolobal with closo-CBn−1Hn-, has been computed at the B3LYP/6-311+G∗∗ level. The most stable positional isomers of closo-BnHn−1CO− have the same structural patterns as those of closo-CBn−1Hn-, and closo-BnHn−1CO− are much less strained than closo-CBn−1Hn-. Energetic analysis identifies closo-B6H5CO−, closo-B8H7CO− and closo-B12H11CO− as the most stable cages. The negative nucleus-independent chemical shifts (NICS) show that closo-BnHn−1CO− are aromatic compounds.