A multinuclear NMR study on the structure and dynamics of lanthanide(III) complexes of the poly(amino carboxylate) EGTA(4-) in aqueous solution
A multinuclear NMR study on the structure and dynamics of lanthanide(III) complexes of the poly(amino carboxylate) EGTA(4-) in aqueous solution
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DOI：
10.1021/ic970240o
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发表时间：
1997-10-22
影响因子：
4.6
通讯作者：
Pubanz, D
中科院分区：
文献类型：
--
作者：
Aime, S;Barge, A;Pubanz, D
[Ln（EGTA）（H2O）]（-）的结构和分子内动力学（Ln = La 3+，Ce 3+，Pr 3+，Nd 3+，Sm 3+，Eu 3+，Gd 3+，Tb 3+，Dy 3+，Ho 3+，Er 3+，Tm 3+，Yb 3+，Lu 3+和EGTA（4-）= 3，12-bis用变温H-1和C-13 NMR研究了（羧甲基）-6，9-二氧杂-3，12-二氮杂十四烷二酸酯（4-）在水溶液中的结构。对质子超精细位移的定量分析和对立体化学非刚性的考虑表明，Sm和Eu之间发生了沿着镧系的结构变化。建议在整个系列中将配位数从10改为9再改为8。来自Gd 3+络合物的O-17 NMR、EPR和匪RD研究的实验数据在同时多参数最小二乘拟合程序中使用自洽理论模型处理（Powell，D. H.的; Ni Dhubhghaill，O. M.; Pubanz，D.; Helm，L.; Lebedev，Y. S.的; Schlaepfer，W.; Merbach，A. E. J. Am.化学分析1996，118，9333）。分子间偶极-偶极电子弛豫机制最近已被描述用于Gd 3+络合物（Powell等人，（同上）包括在数据处理中。[Gd（EGTA）（H2O）]（-）的高水交换率k（ex）（298）=（3.1 +/- 0.2）× 10（7）s（-1）的理论解释为一种限制性解离交换机制（Δ V双匕首= +10.5 +/- 1.0 cm（3）mol（-1）），通过对溶液结构的研究所揭示的水结合位点上的空间限制而有利。
The structures and intramolecular dynamics of [Ln(EGTA)(H2O)](-) (Ln = La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+ and EGTA(4-) = 3,12-bis(carboxymethyl)-6,9-dioxa-3,12-diazatetradecanedioate(4-)) in aqueous solution have been investigated by variable temperature H-1 and C-13 NMR. The quantitative analysis of the proton hyperfine shifts and considerations about the stereochemical nonrigidity indicate the occurrence of a structural change along the lanthanide series with the crossover between Sm and Eu. Changes of coordination number from 10 to 9 to 8 are proposed to occur across the series. The experimental data from O-17 NMR, EPR and NMRD studies for the Gd3+ complex are treated using a self-consistent theoretical model in a simultaneous multiple parameter least-squares fitting procedure (Powell, D. H.; Ni Dhubhghaill, O. M.; Pubanz, D.; Helm, L.; Lebedev, Y. S.; Schlaepfer, W.; Merbach, A. E. J. Am. Chem. Sec. 1996, 118, 9333). An intermolecular dipole-dipole electronic relaxation mechanism that has very recently been described for Gd3+ complexes (Powell et al., op. cit.) is included in the data treatment. The high water exchange rate of [Gd(EGTA)(H2O)](-) of k(ex)(298) = (3.1 +/- 0.2) x 10(7) s(-1) is explained in terms of a limiting dissociative exchange mechanism (Delta V double dagger = +10.5 +/- 1.0 cm(3)mol(-1)), favored by the steric constraints on the water binding site that are revealed by the study on the solution structure.