17O and 183W NMR Diamagnetic and Paramagnetic Shifts in Heterodecatungstates XW10On-36 (X = Ln, Th, U) in Aqueous Solutions Full article
Journal |
Polyhedron
ISSN: 0277-5387 |
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Output data | Year: 1996, Volume: 15, Number: 19, Pages: 3341-3351 Pages count : 11 DOI: 10.1016/0277-5387(96)00029-0 | ||||||
Tags | NUCLEAR MAGNETIC-RESONANCE; COMPLEXES | ||||||
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Abstract:
Heterodecatungstates of the general formula View the MathML source where X = Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Th and U) have been studied by 17O and 183W NMR spectroscopy. It is shown that the structure of the heteropolyanions, where X occupies a centre of a square antiprism formed by two W5O18 ligands and which was determined in the crystalline state, is retained in aqueous solution. Completely resolved 17O and 183W NMR spectra for all atoms, even for the nearest oxygen atoms, have been recorded. From the analysis of the isotropic shifts, the contact and dipolar contributions have been estimated for all constituting atoms. The possible σ- and π-mechanisms of the spin transfer are considered. The negative spin density determines the dominant contact shift for the oxygen and tungsten nearest to X. The large pseudo-contact (ligand centred) contributions are estimated for the nearest oxygen and tungsten atoms. The positive spin density due to the σ-mechanism and large dipolar contribution gives rise to the observed chemical shift for the internal oxygen atom. The other oxygen atoms experience a mostly dipolar contribution with other terms probably cancelling each other. Temperature dependences of the chemical shifts are discussed.
Cite:
Fedotov M.A.
, Samokhvalova E.P.
, Kazansky L.P.
17O and 183W NMR Diamagnetic and Paramagnetic Shifts in Heterodecatungstates XW10On-36 (X = Ln, Th, U) in Aqueous Solutions
Polyhedron. 1996. V.15. N19. P.3341-3351. DOI: 10.1016/0277-5387(96)00029-0 WOS Scopus РИНЦ
17O and 183W NMR Diamagnetic and Paramagnetic Shifts in Heterodecatungstates XW10On-36 (X = Ln, Th, U) in Aqueous Solutions
Polyhedron. 1996. V.15. N19. P.3341-3351. DOI: 10.1016/0277-5387(96)00029-0 WOS Scopus РИНЦ
Dates:
Submitted: | Sep 19, 1995 |
Accepted: | Jan 9, 1996 |
Published print: | Jun 1, 1996 |
Published online: | Jan 15, 1999 |
Identifiers:
Web of science | WOS:A1996UT77200026 |
Scopus | 2-s2.0-0001156553 |
Elibrary | 13245126 |
Chemical Abstracts | 1996:395297 |
Chemical Abstracts (print) | 125:183805 |
OpenAlex | W2001649931 |