Highly variable Zr-CH2-Ph bond angles in tetrabenzylzirconium: Analysis of benzyl ligand coordination modes

Abstract

Analysis of a monoclinic modification of Zr(CH2Ph)4 by single-crystal X-ray diffraction reveals that the bond angles Zr-CH 2-Ph in this compound span a range of 25.1° , which is much larger than previously observed for the orthorhombic form (12.1°). In accord with this large range, density functional theory calculations demonstrate that little energy is required to perturb the Zr-CH2-Ph bond angles in this compound. Furthermore, density functional theory calculations on Me 3ZrCH2Ph indicate that bending of the Zr-CH2-Ph moiety in the monobenzyl compound is also facile, thereby demonstrating that a benzyl ligand attached to zirconium is intrinsically flexible, such that its bending does not require a buffering effect involving another benzyl ligand. © 2012 American Chemical Society.