How big is a Cp? Cycloheptatrienyl zirconium complexes with bulky cyclopentadienyl and indenyl ligands

Abstract

A combination of phase-transfer and traditional alkylation strategies has been employed to synthesise sterically encumbered 1,3-di(cyclohexyl) and 1,3-di(tert-butyl) substituted indenes in multi-gram quantities. These indenyl ligands and sterically demanding alkyl cyclopentadienyl ligands have been used to prepare a series of [(η⁷-C₇H₇)Zr(η⁵-L)] (L = Cp and Ind) complexes by straightforward salt metathesis between [(η⁷-C₇H₇)ZrCl(tmeda)] and the corresponding sodium indenide or cyclopentadienide. All of these Zr complexes have been characterized by elemental analysis, NMR spectroscopy and single crystal X-ray diffraction. The structural information derived from these studies was employed to evaluate the steric demand of these ligands in a realistic manner.