Coordination of Rare-Earth Elements in Complexes with Monovacant Wells-Dawson Polyoxoanions
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- 作者：Qun-Hui Luo ; Robertha C. Howell ; Michaela Dankova ; Judit Bartis ; Clayton W. Williams ; William DeW. Horrocks ; Jr. ; Victor G. Young ; Jr. ; Arnold L. Rheingold ; Lynn C. Francesconi ; and Mark R. Antonio
- 刊名：Inorganic Chemistry
- 出版年：2001
- 出版时间：April 9, 2001
- 年：2001
- 卷：40
- 期：8
- 页码：1894 - 1901
- 全文大小：117K
- 年卷期：v.40,no.8(April 9, 2001)
- ISSN：1520-510X
文摘
The ![]()
C="/images/gifchars/alpha.gif" BORDER=0>-1 and 
chars/alpha.gif" BORDER=0>-2 isomers of the monovacant Wells-Dawson heteropolyoxoanion [P2W17O61]10- are complexantsof trivalent rare-earth (RE) ions and serve to stabilize otherwise reactive tetravalent lanthanide (Ln) and actinide(An) ions in aqueous solution. Aspects of the bonding of Ln ions with chars/alpha.gif" BORDER=0>-1-[P2W17O61]10- and chars/alpha.gif" BORDER=0>-2-[P2W17O61]10-were investigated to address issues of complex formation and stability. We present structural insights about theLn(III) coordination environment and hydration in two types of stoichiometric complexes, [Ln(chars/alpha.gif" BORDER=0>-1-P2W17O61)]7-and [Ln(chars/alpha.gif" BORDER=0>-2-X2W17O61)2]17- (for Ln 
Sm, Eu, Lu; X P, As). The crystal and molecular structures of [(H2O)4Lu(chars/alpha.gif" BORDER=0>-1-P2W17O61)]7- (1) and [Lu(chars/alpha.gif" BORDER=0>-2-P2W17O61)2]17- (2) were solved and refined through use of single-crystalX-ray diffraction. The crystallographic results are supported with corresponding insights from XAFS (X-rayabsorption fine structure) for a series of nine solid-state complexes as well as from optical luminescence spectroscopyof the Eu(III) analogues in aqueous solution. All the Ln ions are eight-coordinate with oxygen atoms in a squareantiprism arrangement. For the 1:1 stoichiometric Ln/chars/alpha.gif" BORDER=0>-1-[P2W17O61]10- complexes, the Ln ions are bound tofour O atoms of the lacunary polyoxometalate framework in addition to four O atoms from solvent (water) moleculesas [(H2O)4Ln(chars/alpha.gif" BORDER=0>-1-P2W17O61)]7-. This structure (1) is the first of its kind for any metal complex ofchars/alpha.gif" BORDER=0>-1-[P2W17O61]10-, and the data indicate that the general stoichiometry [(H2O)4Ln(chars/alpha.gif" BORDER=0>-1-P2W17O61)]7- is maintainedthroughout the lanthanide series. For the 1:2 stoichiometric Ln/chars/alpha.gif" BORDER=0>-2-[X2W17O61]10- complexes, no water moleculesare in the Ln-O8 coordination sphere. The Ln ions are bound to eight O atoms-four from each of twoheteropolyanions-as [Ln(chars/alpha.gif" BORDER=0>-2-X2W17O61)2]17-. The average Ln-O interatomic distances decrease across thelanthanide series, consistent with the decreasing Ln ionic radius.
chars/alpha.gif" BORDER=0>-2 isomers of the monovacant Wells-Dawson heteropolyoxoanion [P2W17O61]10- are complexantsof trivalent rare-earth (RE) ions and serve to stabilize otherwise reactive tetravalent lanthanide (Ln) and actinide(An) ions in aqueous solution. Aspects of the bonding of Ln ions with chars/alpha.gif" BORDER=0>-1-[P2W17O61]10- and chars/alpha.gif" BORDER=0>-2-[P2W17O61]10-were investigated to address issues of complex formation and stability. We present structural insights about theLn(III) coordination environment and hydration in two types of stoichiometric complexes, [Ln(chars/alpha.gif" BORDER=0>-1-P2W17O61)]7-and [Ln(chars/alpha.gif" BORDER=0>-2-X2W17O61)2]17- (for Ln Sm, Eu, Lu; X P, As). The crystal and molecular structures of [(H2O)4Lu(chars/alpha.gif" BORDER=0>-1-P2W17O61)]7- (1) and [Lu(chars/alpha.gif" BORDER=0>-2-P2W17O61)2]17- (2) were solved and refined through use of single-crystalX-ray diffraction. The crystallographic results are supported with corresponding insights from XAFS (X-rayabsorption fine structure) for a series of nine solid-state complexes as well as from optical luminescence spectroscopyof the Eu(III) analogues in aqueous solution. All the Ln ions are eight-coordinate with oxygen atoms in a squareantiprism arrangement. For the 1:1 stoichiometric Ln/chars/alpha.gif" BORDER=0>-1-[P2W17O61]10- complexes, the Ln ions are bound tofour O atoms of the lacunary polyoxometalate framework in addition to four O atoms from solvent (water) moleculesas [(H2O)4Ln(chars/alpha.gif" BORDER=0>-1-P2W17O61)]7-. This structure (1) is the first of its kind for any metal complex ofchars/alpha.gif" BORDER=0>-1-[P2W17O61]10-, and the data indicate that the general stoichiometry [(H2O)4Ln(chars/alpha.gif" BORDER=0>-1-P2W17O61)]7- is maintainedthroughout the lanthanide series. For the 1:2 stoichiometric Ln/chars/alpha.gif" BORDER=0>-2-[X2W17O61]10- complexes, no water moleculesare in the Ln-O8 coordination sphere. The Ln ions are bound to eight O atoms-four from each of twoheteropolyanions-as [Ln(chars/alpha.gif" BORDER=0>-2-X2W17O61)2]17-. The average Ln-O interatomic distances decrease across thelanthanide series, consistent with the decreasing Ln ionic radius.