Obtaining accurate chemical shifts for all magnetic nuclei (1H, 13C, 17O, and 27Al) in tris(2,4-pentanedionato-O,O′)aluminium(III) - A solid-state NMR case study

We report a complete set of high-resolution solid-state NMR spectra for all magnetic nuclei (H-1, C-13, O-17, and Al-27) in the alpha-form of tris(2,4-pentanedionato-O,O')aluminium(III), alpha-Al(acac)(3). These high-resolution NMR spectra were obtained by using a host of solid-state NMR techniques: standard cross-polarization under the magic-angle spinning (CPMAS) method for C-13, 1-D homonuclear decoupling using the windowed DUMBO sequence for H-1, double-rotation (DOR) for O-17 and Al-27, and multiple-quantum MAS for Al-27. Some experiments were performed at multiple magnetic fields. We show that the isotropic chemical shifts obtained for H-1, C-13, O-17, and Al-27 nuclei in alpha-Al(acac)(3) are highly resolved and accurate, regardless of the nature of the targeted nuclear spins (i.e., spin-1/2 or quadrupolar) and, as such, can be treated equally in comparison with computational chemical shifts obtained from a gauge-including projector-augmented wave (GIPAW) plane-wave pseudopotential DFT method.