Zirconocene complexes of the sterically demanding pentaphenylcyclopentadienyl ligand,Cp~(PRO).Synthesis and characterization of Cp~(PRO)ZrCl_3 and CpCp~(PRO) ZrCl_2 (Cp=#eta#~5-C_5H_5;Cp~(PRO)=#eta#~5-C_5(C_6H_5)_5)

摘要

The synthesis,characterization and X-ray structures of two zirconium complexes of the bulky pentaphenylcyclopentadienyl ligand,Cp~(PRO),are reported.The monocyclopentadienyl 12 electron complex,Cp~(PRO)ZrCl_3 (I),has an unusual monomeric structure in the solid state and has short Zr-ligand distances.The Lewis acidity of this complex is manifested in its ability to catalyze the [4+2] cycloadditions of methyl-and ethylmethacrylate to cyclopentadiene.The sandwich complex,Cp~(PRO)CpZrCl_2 (II),has more typical Zr-ligand distances,but has a more parallel arrangement of the two cyclopentadienyl rings.