Isomers of disilabenzene (C₄Si₂H₆): a computational study

Abstract

Computational studies using density functional theory (B3LYP) and coupled cluster (CCSD(T)) method were performed on a large number of isomers of disilabenzene, C₄Si₂H₆. In all, 78 stationary points were identified, wherein 61 of them correspond to the minima on the C₄Si₂H₆ potential energy surface. Although the planar forms correspond to the most stable isomers, several unconventional structures are highly competitive in energy. While the framework is an important factor, the substitution pattern seems to be equally important in deciding the relative stabilities of the isomers of disilabenzenes. The relative energies of valence isomeric forms are compared with those of benzene, silabenzene, and diphosphabenzene isomers. The relative energy orderings of all the isomers are analyzed, and conclusions about the stability are drawn. Several H-bridged isomers were computed to be very stable. Several monocyclic six-membered ring structures, where the 6π-aromaticity is disturbed, also indicated the flatness of the potential energy surface of disilabenzene and their propensity toward high reactivity and facile rearrangements.