NMR Study of uronic acids and their complexation with molybdenum(VI) and tungsten(VI) oxoions
作者:M. Luisa、D. Ramos、M. Madalena、M. Caldeira、Victor M.S. Gil
DOI:10.1016/0008-6215(96)00050-x
日期:1996.6
evidence was gathered for the formation of two 1:2 (metal-ligand) complexes of W(VI) with the furanose forms. These are stronger with d -galacturonic acid and when the β forms are involved. The same was found with Mo(VI), but, in addition, 2:1 complexes also form. In the case of d -galacturonic acid, three such complexes were detected, two involving the α-pyranose form, in an approximately 4 C 1 , and
摘要进行了d-半乳糖醛酸和d-葡萄糖醛酸在水溶液中的多核一维和二维NMR研究,以及它们在不同浓度和pH条件下与钨酸盐和钼酸根离子的络合作用。酸主要以吡喃糖形式存在,但检测到的络合物涉及不稳定的α-和β-呋喃糖异构体以及α-吡喃糖形式。因此,NMR证据收集了呋喃糖形式的W(VI)的两个1:2(金属-配体)配合物的形成。当涉及β形式时,它们对d-半乳糖醛酸更强。对于Mo(VI)也发现了同样的情况,但此外,还形成了2:1的络合物。在d-半乳糖醛酸的情况下,检测到3种此类复合物,其中2种涉及α-吡喃糖形式,分别为大约4 C 1和1 C 4构象。另一个可能涉及β-呋喃糖异构体。用d-葡萄糖醛酸,只能鉴定出一种这样的复合物,它以扭曲的1 C 4构象涉及α-吡喃糖异构体。从1 H,13 C,17 O,95 Mo和183 W NMR数据获得有关各种配合物结构的更详细的信息。具有α-吡喃糖形式的2:1配合物