Synthesis and characterization of Zr(IV) and Y(III) complexes with monocyclopentadienyl ligands containing an additional site tethered by a coordinating 2,6-pyridine bridge. X-ray crystal structures of the zirconium complexes

A new monocyclopentadienyl ligand containing an additional site tethered by a coordinating 2,6-pyridine unit has been prepared, rac-2-(1¢¥-hydroxy-2¢¥,2¢¥-dimethylpropyl)-6-(1¡È,1¡È-dimethyl-cyclopentadienylmethyl) pyridine dilithium salt, LLi2 ( rac-4) that is analogous to the ligands present in CGC. After reacting the dilithium salt of the ligand with ZrCl4 in a molar ratio of 1:1 in THF the complex LZrCl2¡¤THF ( rac-5) was obtained which forms an insoluble oligomeric species after the loss of THF upon purification. From the mater liquor two crystalline species of the formula LHZrCl3 ( rac-6) and LH2ZrCl4¡¤THF ( rac-7) were isolated, whose X-ray crystal structures are reported. The reaction of LLi2 with Y(OTf)3 afforded the probably dimeric species [LYOTf]2 ( rac-8) from which the complex [LY(CH2Si(CH3)3)]2 ( rac-9) was obtained after reaction with LiCH2Si(CH3)3.