Ma W, van Koningsveld H, Peters J A, Maschmeyer T
Laboratory for Applied Organic Chemistry and Catalysis, Delft University of Technology, The Netherlands.
Chemistry. 2001 Feb 2;7(3):657-63. doi: 10.1002/1521-3765(20010202)7:3<657::aid-chem657>3.0.co;2-6.
The structures of complexes of Zr(IV) and oxydiacetate (ODA2-) in aqueous solutions of pH 0-7 were investigated with the use of 1H, 13C, and 17O NMR spectroscopy. Equilibria of mononuclear [Zr(oda)]2+, [Zr(oda)2], and [Zr(oda)3]2- complexes have been observed. In all complexes ODA2- is bound in a tridentate fashion through the two carboxylate groups and the ether oxygen. No di- or oligonuclear species containing ODA2- were observed. An excess of free Zr(IV) remains in solution, probably as a result of weak electrostatic interactions between negatively charged Zr-ODA complexes or free ODA2- and a positively charged cyclic tetranuclear hydroxy zirconium complex. CP-MAS 13C NMR spectra of solid compounds isolated from the samples indicated that the structures of the [Zr(oda)2] and [Zr(oda)3]2- complexes in solution are similar to those in the solid state. This is corroborated by the single-crystal X-ray structure of Na2[Zr(oda)3] x 5.5 H2O, which was obtained from a solution containing exclusively the [Zr(oda)3]2- complex. In this structure Zr(IV) is nine-coordinate with the three ODA2- ligands bound in a tricapped trigonal prismatic geometry. The negative charge of this [Zr(oda)3]2complex is balanced by two Na+ ions, one of which is on a center of symmetry between delta and lambda enantiomers of [Zr(oda)3]2-. This Na+ is octahedrally coordinated to six (non Zr(IV)-bound) carboxylate oxygen atoms of six different [Zr(oda)3]2- units.
利用¹H、¹³C和¹⁷O核磁共振光谱研究了pH值为0 - 7的水溶液中Zr(IV)与氧化二乙酸根（ODA²⁻）配合物的结构。观察到单核[Zr(oda)]²⁺、[Zr(oda)₂]和[Zr(oda)₃]²⁻配合物的平衡。在所有配合物中，ODA²⁻通过两个羧酸根基团和醚氧以三齿方式结合。未观察到含有ODA²⁻的二核或多核物种。溶液中残留有过量的游离Zr(IV)，这可能是由于带负电荷的Zr - ODA配合物或游离ODA²⁻与带正电荷的环状四核羟基锆配合物之间的弱静电相互作用所致。从样品中分离出的固体化合物的CP - MAS ¹³C核磁共振光谱表明，溶液中[Zr(oda)₂]和[Zr(oda)₃]²⁻配合物的结构与固态时相似。这一点由Na₂[Zr(oda)₃]·5.5H₂O的单晶X射线结构得到证实，该结构是从仅含有[Zr(oda)₃]²⁻配合物的溶液中获得的。在此结构中，Zr(IV)为九配位，三个ODA²⁻配体以三帽三棱柱几何构型结合。[Zr(oda)₃]²⁻配合物的负电荷由两个Na⁺离子平衡，其中一个位于[Zr(oda)₃]²⁻的δ和λ对映体之间的对称中心上。这个Na⁺与六个不同[Zr(oda)₃]²⁻单元的六个（非与Zr(IV)结合的）羧酸根氧原子呈八面体配位。
