rac-[1,2-ethylene-1,1'-bis(eta(5)-tetrahydroindenyl)][eta(2)-bis(trimethylsilyl)acetylene]zirconium, the first zirconocene-alkyne complex without additional ligands: Synthesis, reactions, and X-ray crystal structure

The reduction of rac-(EBTHI)ZrCl2 [EBTHI = 1,2-ethylene-1,1'-bis(eta(5)-tetrahydroindenyl)] with equimolar amounts of magnesium in the presence of Me(3)SiC(2)SiMe(3) in THF at room temperature gave the first zirconocene-alkyne complex containing no additional ligands, rac-(EBTHI)Zr(eta(2)-Me(3)SiC(2)SiMe(3)), 2. With pyridine and (S)-(-)-nicotine complex 2 gave the ligand-containing complexes rac-(EBTHI)Zr(L)(eta(2)-Me(3)SiC(2)SiMe(3)) (L = pyridine, 3; L = (S)(-)-nicotine, 4). In the reaction of 2 with acetone the insertion product rac-(EBTHI)(ZrOCMe(2)C(SiMe(3))=C(SiMe(3)), 5, was formed. Complex 2 reacted with 2 equiv of PhN=CHPh with substitution of the alkyne to form rac-(EBTHI)ZrNPhCHPhCHPhNPh, 6. Compounds 2 and 6 were characterized by an X-ray structure analysis.