Preparation of organozirconium aromatic compounds in mixed aqueous-organic solvents: X-ray structures of [Cp 2ZrCl(μ 2-O′,O′′C-C 6H 5)], [(CpZr) 3(μ 2-O′,O′′C-C 6H 3Cl 2) 3(μ 3-OH)(μ 2-OH) 3](Cl 2C 6H 3COO) 2, and [(CpZr) 3(μ 2-O′,O′′C-C 6H 4Cl) 3(μ 3-OH)(μ 2-OH) 3]Cl 2·CH 2Cl 2

Abstract

A new and facile method is presented for the synthesis of zirconocene carboxylate compounds, in which zirconocene dichloride (Cp 2ZrCl 2) is dissolved in 1 M aqueous HCl solution and the requisite ligand is dissolved in an organic solvent. Five such compounds [Cp 2ZrCl(μ 2-O′,O′′C-C 6H 5)] ( 1), [Cp 2ZrCl(μ 2-O′,O′′C-C 6H 3Cl 2)] ( 2), [Cp 2Zr(μ 2-O′,O′′C-C 6H 3(OH)Cl) 2] ( 3), [Cp 2Zr(μ 2-O′,O′′C-C 6H 3(OH)(NO 2)) 2] ( 4), and [Cp 2Zr(μ 2-O′,O′′C-C 6H(OH)Cl 3) 2] ( 5) have been obtained by this method. The effect of pH on the stability of Cp 2ZrCl 2 in 1 M HCl solution has been investigated by UV/vis spectrophotometry and 1H NMR spectrometry. The results showed that the aqueous Cp 2ZrCl 2 solutions became less stable with increasing pH, liberating cyclopentadiene. Accordingly, at higher pH (∼7), two trinuclear zirconium monocyclopentadienyl compounds, [(CpZr) 3(μ 2-O′,O′′C-C 6H 3Cl 2) 3(μ 3-OH)(μ 2-OH) 3](Cl 2C 6H 3COO) 2 ( 6) and [(CpZr) 3(μ 2-O′,O′′C-C 6H 4Cl) 3(μ 3-OH)(μ 2-OH) 3]Cl 2·CH 2Cl 2 ( 7), were obtained. All compounds 1– 7 have been characterized by FT-IR, 1H NMR spectra and elemental analysis. In all of the compounds, the aromatic acid acts as a bidentate ligand in coordinating to the zirconium; both chelating and bridging modes are observed. X-ray crystallographic studies on 1, 6, and 7 have revealed that the geometries at zirconium are distorted octahedral in 6 and 7, and distorted trigonal-bipyramidal in 1.