Studies on tris(β-diketonato)zirconium (IV); syntheses, characterization and catalytic activity for ring opening of oxiranes

Two series of zirconium β-diketonates: tris(benzoylacetonato)zirconium (IV) perchlorate (3b) and tris(dibenzoylmethanato)zirconium (IV) perchlorate (3c) were synthesized. The complexes were synthesized by a reaction of zirconium tetrachloride with corresponding ligands in a 1:3 molar ratio, followed by a reaction with silver perchlorate. Characterization was by elemental analyses, UV-Vis, FTIR and 1H NMR spectroscopies. The complexes were prospective to serve as Lewis acid catalysts for ring opening reactions of oxiranes with alcohols for synthesizing primary alkoxyalcohols. Previously reported tris(acetylacetonato)zirconium (IV) chloride (2a) was used as comparison. The effect of phenyl ring on ligand frame towards enhancement of Lewis acidity of zirconium is focused. Other factors, such as nucleophile strength of alcohols and alkyl substituent of oxiranes are also discussed.