Facile valence isomerization among bis(silacyclopropenyl), disila(Dewar benzene) and disilabenzvalene

Hybrid density functional theory (B3LYP) and ab initio (CCSD(T)) calculations were performed to explore the reaction energy pathways of the valence isomerizations among the disilabenzene isomers, namely, bis(silacyclopropenyl) (1), disila(Dewar benzene) (3) and disilabenzvalene (4). The computational study predicts that the interconversion of 1 to 3 and 4 occurs spontaneously. However, the interconversion between Dewar benzene (3) and benzvalene (4) analogs is a multistep process involving a new intermediate structure 2a, with energy barriers lying above 30 kcal/mol in energy compared to 3 and 4.