Synthesis of the Dibismuthene Complex [{μ-η2-(cis-Me3SiCH2Bi)2}{W(CO)5}2] from a Cyclobismuthane and [W(CO)5(thf)]

The wings of the butterfly structure are widely extended in 2 (see picture, R=Me3SiCH2), a complex with a dibismuthene ligand, which coordinates as a “side-on”-bridging, four-electron donor to two tungsten atoms. Complex 2 is formed from the reaction of [W(CO)5(thf)] with alkylbismuth five- and three-membered rings of cyclobismuthanes 1, which exist in equilibrium.