Influence of Steric and Electronic Properties of the Defect Site, Lanthanide Ionic Radii, and Solution Conditions on the Composition of Lanthanide(III) ![]()
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- 作者：Cheng Zhang ; Robertha C. Howell ; Qun-Hui Luo ; Heidi L. Fieselmann ; Louis J. Todaro ; and Lynn C. Francesconi
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：May 16, 2005
- 年：2005
- 卷：44
- 期：10
- 页码：3569 - 3578
- 全文大小：324K
- 年卷期：v.44,no.10(May 16, 2005)
- ISSN：1520-510X
文摘
This study identifies the principles that govern the formation and stability of Ln complexes of the (
chars/alpha.gif" BORDER=0>1-P2W17O61)10-isomer. The conditional stability constants for the stepwise formation equilibria, K1cond and K2cond, determined by31P NMR spectroscopy, show that the high log K1cond/log K2cond ratio predicts the stabilization of the 1:1 Ln/(chars/alpha.gif" BORDER=0>1-P2W17O61)10- species. The value of log K1cond increases as the Ln series is traversed, consistent with the highcharge/size requirement of the basic chars/alpha.gif" BORDER=0>1 defect site. The conditional stability constants, K2, are very low and arehighly dependent on the countercations in the buffer. The source of the instability is understood from the crystalstructures of the early-mid lanthanide analogues, where the close contact of the (chars/alpha.gif" BORDER=0>1-P2W17O61)10- units result insevere steric encumbrance. The electronic properties of the chars/alpha.gif" BORDER=0>1 defect along with the lanthanide ionic radii andcountercation composition are important parameters that need to be considered for a rational synthesis of lanthanidepolyoxometalates.
chars/alpha.gif" BORDER=0>1-P2W17O61)10-isomer. The conditional stability constants for the stepwise formation equilibria, K1cond and K2cond, determined by31P NMR spectroscopy, show that the high log K1cond/log K2cond ratio predicts the stabilization of the 1:1 Ln/(chars/alpha.gif" BORDER=0>1-P2W17O61)10- species. The value of log K1cond increases as the Ln series is traversed, consistent with the highcharge/size requirement of the basic chars/alpha.gif" BORDER=0>1 defect site. The conditional stability constants, K2, are very low and arehighly dependent on the countercations in the buffer. The source of the instability is understood from the crystalstructures of the early-mid lanthanide analogues, where the close contact of the (chars/alpha.gif" BORDER=0>1-P2W17O61)10- units result insevere steric encumbrance. The electronic properties of the chars/alpha.gif" BORDER=0>1 defect along with the lanthanide ionic radii andcountercation composition are important parameters that need to be considered for a rational synthesis of lanthanidepolyoxometalates.