Group 14 Triple-Decker Cations

The triple-decker cations trans-[(Cp*Sn)(2)(mu-eta(5):eta(5)-Cp*)](+) and traps-[(Cp*Pb)(2)(mu-eta(5):eta(5)-Cp*)](+) have been prepared and structurally characterized as their [B(C6F5)(4)](-) salts from the reactions of [Cp*M][B(C6F5)(4)] (M = Sn, Pb) with the appropriate decamethylmetallocene. Both triple-decker cations adopt a cisoid arrangement of terminal Cp* groups, whereas the two known triple-decker main-group anions possess a transoid arrangement of terminal Cp groups. The reason for this conformational difference has been probed on the basis of DFT calculations.