Acta Crystallographica Section B

Structural Science

Volume 54, Part 4 (August 1998)

research papers

Acta Cryst. (1998). B54, 431-437 [ doi:10.1107/S0108768197017771 ]

Structures of Homoleptic Benzyl Derviatives of Zirconium

C. Tedesco, A. Immirzi and A. Proto

Abstract: Crystals of Zr(p-CH₂C₆H₄CMe₃)₄, tetra(4-tert-butylbenzyl)zirconium (1), have been studied by X-ray diffraction. The crystals belong to the tetragonal system, space group I4, with a = 16.481 (2), c = 7.131 (4) Å, so that chemically equivalent ligands are also structurally equivalent, unlike other known homoleptic M(CH₂C₆H₅)₄ compounds. Zr-CH₂-C_ipso bond angles of 90.0 (2)° suggest that ligands are [eta] ²-bonded. The structure is discussed along with that of Zr(CH₂C₆H₅)₄, tetrabenzylzirconium (2) (redetermined), which is crystallographically unsymmetrical but also of approximate S₄ symmetry. The distortion of (2) from tetragonal symmetry (the four Zr-CH₂-C_ipso bond angles being rather different) is discussed along with crystal packing.