Reactions of Cp2M(PMe3)2 complexes (M = Ti, Zr) with acetylenes. Selective formation of trans-polyacetylene at low temperatures

Article abstract of DOI:10.1016/S0022-328X(00)98895-8

The reaction of Cp2Ti(PMe3)2 with C2H2 gives the substitution product Cp2Ti(C2H2)(PMe3), the titanacyclopentadiene (Cp2Ti(C4H4) and trans-polyacetylene.A mechanism of the catalytic formation of polyacetylene is proposed.Substituted acetylenes R¹C2R² (R¹ <*> R² = H, Me, Ph) react with Cp2Ti(PMe3)2 in an analogous manner except that no polyalkynes are produced.The Zr derivative Cp2Zr(PMe3)2 and C2H2 yield the labile Cp2Zr(C2H2)(PMe3).