Vanadium(V) oxyanions: Interactions of vanadate with 1,1,1-tris(hydroxymethyl)ethane and with the buffer tris(hydroxymethyl)aminomethane
Vanadium(V) oxyanions: Interactions of vanadate with 1,1,1-tris(hydroxymethyl)ethane and with the buffer tris(hydroxymethyl)aminomethane
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钒 (V) 氧阴离子：钒酸盐与 1,1,1-三（羟甲基）乙烷以及缓冲剂三（羟甲基）氨基甲烷的相互作用
DOI：
10.1021/ic00280a036
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发表时间：
1988
影响因子：
4.6
通讯作者：
M. Gresser
中科院分区：
文献类型：
--
作者：
A. Tracey;M. Gresser
用/SUP-51/V核磁共振波谱研究了钒酸根与1，1，1-三羟甲基乙烷(tris-ETH)及缓冲液三羟甲基氨基甲烷的相互作用。研究发现，在pH为7.5的条件下，钒酸根与三乙醇胺反应生成多种产物。根据钒酸盐和配体浓度的变化，可以得到各种产物的配体化学计量比和生成常数。鉴定的产物包括钒酸单酯、钒酸二酯单酯和双酯，以及一个双核产物，提出了每个钒核的双锥配位几何构型。Tris缓冲液与钒酸根的反应类似于Tris-ETH。在pH 7.6和9.0条件下的研究表明，钒酸盐形成了四面体配位的钒酸酯，这是一种指定为八面体配位的双(配体)产物，以及两个双核产物，一个带有一个Tris配体，另一个带有两个配体。结果与第一种情况下的双锥/四面体混合酸酐和第二种情况下类似于三乙基乙酸乙酯的对称双锥酸酐的结果相一致。一个相当令人惊讶的观察是，这两个产品表现出很大的化学位移对pH的依赖，推测反映了More？Tris的氨基的质子化/去质子化。研究了在顺式或反式-1，2-环己二醛存在下以及在有或没有Tris缓冲液的情况下，Tris与钒酸盐与两种二元醇的反应产物之间的强烈协同反应。这一结果表明，在研究钒酸盐/配体相互作用时，应极其谨慎地使用Tris缓冲液。参考文献14，图6。
/sup 51/V NMR spectroscopy has been used to study the interactions of vanadate with 1,1,1-tris(hydroxymethyl)ethane (tris-eth) and with the buffer tris(hydroxymethyl)aminomethane. The reaction of vanadate with tris-eth was found to proceed readily at pH 7.5 to give a variety of products. From variation of vanadate and ligand concentration it was possible to obtain the ligand stoichiometry and formation constants for the various products. The products identified included the monoester of vanadate, the mono- and diesters of divanadate, and a binuclear product for which a bipyramidal coordination geometry about each vanadium nucleus was proposed. The reaction of Tris buffer with vanadate was similar to that of tris-eth. Studies at pH 7.6 and 9.0 showed the formation of vanadate esters of tetrahedral coordination, a bis(ligand) product, assigned an octahedral coordination, and, as well, two binuclear products, one with a single Tris ligand and the second with two ligands. The results were consistent with a bipyramidal/tetrahedral mixed anhydride in the first case and a symmetrical bipyramidal anhydride analogous to that formed with tris-eth in the second case. A rather surprising observation was that these two products exhibited a large chemical shift dependence on pH, presumably reflecting the protonation/deprotonation of the amino group ofmore » Tris. Investigation of vanadate in the presence of cis- or trans-1,2-cyclohexanedial and with or without Tris buffer revealed a strong synergistic reaction of tris with the products of the reaction of vanadate with either of the diols. This result suggests that Tris buffer should be used with extreme caution when vanadate/ligand interactions are studied. 14 refs., 6 figs.« less