59Co Chemical Shift Anisotropy and Quadrupole Coupling for K3Co(CN)6 from MQMAS and MAS NMR Spectroscopy

✍ Scribed by Ulla Gro Nielsen; Hans J. Jakobsen; Jørgen Skibsted

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 120 KB
• Volume: 20
• Category: Article
• ISSN: 0926-2040
• DOI: 10.1006/snmr.2001.0027

✦ Synopsis

Co triple-quantum (3Q) MAS and single-pulse MAS NMR spectra of K 3 Co(CN) 6 have been obtained at 14.1 T and used in a comparison of these methods for determination of small chemical shift anisotropies for spin I = 7/2 nuclei. From the 3QMAS NMR spectrum a spinning sideband manifold in the isotropic dimension with high resolution is reconstructed from the intensities of all spinning sidebands in the 3QMAS spectrum. The chemical shift anisotropy (CSA) parameters determined from this spectrum are compared with those obtained from MAS NMR spectra of (i) the complete manifold of spinning sidebands for the central and satellite transitions and of (ii) the second-order quadrupolar lineshapes for the centerband and spinning sidebands from the central transition. A good agreement between the three data sets, all of high precision, is obtained for the shift anisotropy (δ σ = δ iso -δ zz ) whereas minor deviations are observed for the CSA asymmetry parameter (η σ ). The temperature dependence of the isotropic 59 Co chemical shift has been studied over a temperature range from -28 to +76 • C. A linear and positive temperature dependence of 0.97 ppm/ • C is observed.