Crystal structures of hafnium(IV) and zirconium(IV) complexes with β-diketones

Abstract

Preparation methods are developed for a number of 7- and 8-coordinated derivatives of Hf(IV) and Zr(IV) with β-diketonate ligands (R1-CO-CH-CO-R2). The complexes obtained are examined by IR spectroscopy, mass spectrometry, and X-ray crystallography. All structures are molecular. The M-O distances fall within 2.09–2.28 A. In the crystals, the molecules are joined only by van der Waals interactions. It is demonstrated that the series of hafnium(IV) and zirconium(IV) chelates with identical ligands are isostructural, and the introduction of CF3- or tert-butyl groups in the terminal positions of the ligand as well as chlorine substitution for one of the ligands do not essentially affect the basic geometric characteristics of the ligand in the complexes.