A new strategy for hyperconjugative antiaromatic compounds utilizing negative charges: a dibenzo[,]silepinyl dianion

Herein we propose a new strategy for hyperconjugative antiaromatic compounds utilizing negative charges and design the 5,5-diphenyldibenzo[ b , f ]silepinyl dianion (pseudo 16π-electron system) in which negative hyperconjugation occurs between the anionic π-cloud and the σ*(Si-Ph) orbital. Essentially, reduction of the dibenzo[ b , f ]silepin with lithium readily generated a dilithium salt of the dibenzosilepinyl dianion, and its hyperconjugative antiaromaticity has been evidenced by the upfield shifts of 1 H NMR signals and theoretical calculations, including large NICS zz values and ACID plots. Based on a new strategy of utilizing negative charges, a dibenzo[ b , f ]silepinyl dianion was synthesized and its hyperconjugative antiaromatic character is disclosed using NMR studies, large NICS zz values, and ACID plots.