Heavier Carbon Subchalcogenides as C₃ Sources for Tungsten-Capped Cumulenes: A Theoretical Study

Heavier carbon subchalcogenides C₃E₂ (E = S, Se) can bind to transition metals through either a C═C or a C═E double bond. These two binding modes on a reactive tungsten (PMe₃)₄WCl₂ site have been explored by density functional theory methods (M06-L/DZP+Lanl2DZ). The important step controlling the reaction direction is the initial binding of the C₃E₂ ligand. Of particular significance is the M═C═C═C═E fragment resulting from the C═E coordination mode. This fragment can bind to additional C₃E₂ molecules or bridge to other metals. Ultimately C₃E₂ serves as a source of C₃ units for building C_3n carbon sp-hybridized allotropes.