On the assignment of (19)F MAS NMR spectra of fluoroaluminates using through-space spectral edition of (19)F-(27)Al and (19)F-(19)F connectivities

Charlotte Martineau; Christophe Legein; Jean-Yves Buzaré; Franck Fayon

doi:10.1039/b812091a

On the assignment of (19)F MAS NMR spectra of fluoroaluminates using through-space spectral edition of (19)F-(27)Al and (19)F-(19)F connectivities

Phys Chem Chem Phys. 2009 Feb 14;11(6):950-7. doi: 10.1039/b812091a. Epub 2008 Dec 9.

Authors

Charlotte Martineau¹, Christophe Legein, Jean-Yves Buzaré, Franck Fayon

Affiliation

¹ Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Le Mans Cedex 9, France. charlotte.martineau.etu@univ-lemans.fr

PMID: 19177213
DOI: 10.1039/b812091a

Abstract

Advantages and limitations of (19)F-(27)Al and (19)F-(19)F dipolar-based 2D NMR experiments for (19)F MAS spectra assignments of fluoroaluminates are presented. In beta-BaAlF(5), combination of 2D MAS (19)F-(27)Al CP-HETCOR and (19)F-(19)F DQ-SQ NMR correlation experiments allows complete unambiguous assignment of the ten poorly resolved resonances of same relative intensities of the (19)F MAS NMR spectrum. The gain in resolution of the (19)F MAS 2D spectrum compared to a 1D spectrum is evidenced, allowing distinction of the two shared-fluorine resonances of Ba(3)Al(2)F(12). Limitations of the (19)F MAS DQ-SQ NMR experiment are shown for Ba(3)Al(2)F(12) and for alpha-CaAlF(5). For beta-BaAlF(5) and Ba(3)Al(2)F(12), final line assignments question those previously established from (19)F isotropic chemical shift calculations, which demonstrate that such experiments are essential for correct line assignments and assessment of calculation results.