Roles of (pi)-Alkyne, Hydride-Alkynyl, and Vinylidene Metal Species in the Conversion of Alkynes into Vinylidene: New Theoretical Insights

The new compounds K4Nb2S10O and Rb4Nb2S10O have been synthesized by the reaction of potassium or rubidium alkaline polychalcogenides with NbO2, Nb2O5, or mixtures of Nb and NbO. Their structures consist of discrete [Nb2Q11]4- anions (Q = O, S) built up of two face-sharing pentagonal bipyramids, which are connected via the alkali metal cations.