Sandwich-like compounds based on bare all-boron cluster B(6)(2-).

Here, we theoretically predict antiaromatic double-decked compounds [DMB(6)](q-) (D = B(6)(2-), Cp(-); M = Li, Na, K, Be, Mg, Ca) as well as the triple-decked sandwich-like species. Being energetically higher than the fusion isomers, the homo-decked assembly species [B(6)MB(6)](q-) without and with counterions are less likely to be observed experimentally. The hetero-decked sandwich species are low-lying minima containing double-fold antiaromatic B(6)(2-) building blocks. Additionally, the well-retained double antiaromaticity is mainly ascribed to the ionic electrostatic interaction and the protection of rigid Cp-deck in order to avoid the fusion of B(6)(2-). Our results represent the first example that the antiaromaticity is well retained in assembled compounds as in the free B(6)(2-) cluster. Realization of the double antiaromatic B(6)(2-)-incorporated assembled compound is very promising.