Applications of vanadium-51 and phosphorus-31 nuclear magnetic resonance spectroscopy to the study of iso- and hetero-polyvanadates

摘要: Vanadium-51 n.m.r. spectra of a number iso- and hetero-polyvanadate anions are reported. Spectra solutions containing [V10O28]6–(pH 6.5–3.5) consistent with the known solid-state structure this anion. The [VO2]+ cation in aqueous solution almost certainly has an octahedral cis-dioxo-structure as its linewidth is comparable those for cis compounds [VO2(04C2)2]3– [VO2(edta)]3–(edta = ethylenediaminetetra-acetate), which broader than pseudo-tetrahedral [VCl2O2]– [VF2O2]–. Chemical shifts pseudo-octahedral vanadium atoms [VxW6–xO19]n–. [PVxW12–xO40]n–. [PMo12–xVxO40]n–, [VVxW12–xO40]n– range from 506 to 545 p.p.m. (VCl3O reference) linewidthsfrom 60 200 Hz (2.6–9 p.p.m.). Multiple lines specta 1 : 12 (Keggin) heteropolyanions confirm existence geometrical isomers distinguished by relative positions two or more polyanion structure. Phosphorus-31 that most if not all possible type areformed. chemical 31P [PMo12040]3– [PW12040]3– ca. 11 21 upfield unprotonated [PO4]3– ion (–6 respect 85% H,PO,). Introduction V heteropoly structures causes progressive decrease shift, enabling mixtures such Keggin be analyzed A parallel variation 51V shift found [VO4]3–(536) tetrahedral [VV3W9040]6–(553) [VV2W10O40]5–(556