Zirconium complexes of amino(polyphenolic) ligands and their hydrolytic stability

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• 作者：Jy D. Chartres ; Ahmed Dahir ; Peter A. Tasker ; Fraser J. White
• 关键词：Zirconium complexes ; Phenolic ligands ; Phenolate complexes
• 刊名：Inorganic Chemistry Communications
• 出版年：2007
• 出版时间：October 2007
• 年：2007
• 卷：10
• 期：10
• 页码：1154-1158
• 全文大小：259 K

文摘

Three amino(polyphenolic) ligands, N,N′-bis(5-tert-butyl-2-hydroxybenzyl)-1,2-diaminoethane 1, tris(5-tert-butyl-2-hydroxy-3-methylbenzyl)amine 3, its 3-chloro analogue 4 and their Zr^IV complexes have been synthesised. The crystal structure of the Zr^IV complex of tris(5-tert-butyl-3-chloro-2-hydroxybenzyl)amine, shows this to be [Zr(4-2H)₂] in which both ligands exists in a zwitterionic form with one alkylammonium and three phenolate groups. The complexes are stable in a two phase, chloroform/water, system at high pH, but the zirconium is stripped at pH < 2.5. The pH value needed to strip 50 % of the Zr^IV from the complex [Zr(1-4H)] of the tetraphenolic ligand is 2.0 whilst the complexes [Zr(3-2H)₂] and [Zr(4-2H)₂] of the triphenolic ligands are slightly more stable with pH_1/2 values of 1.4. We were unable to use the ligands to extract zirconium from low pH aqueous zirconium oxychloride solutions into an organic phase under a variety of conditions.