Taking advantage of an order of magnitude in sensitivity enhancement obtained by sampling of quadrupolar-echo (QE) solid-state NMR spectra during a quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) pulse sequence, we demonstrate that the coordination environment of low-γ quadrupolar metal nuclei can be studied routinely for powders with these nuclei in natural abundance. The general applicability of the method is demonstrated by 39 K, 25 Mg, 67 Zn, and 87 Sr QCPMG solid-state NMR experiments for K 2 MoO 4 , KVO 3 , Mg(VO 3 ) 2 , Zn(CH 3 COO) 2 ‚2H 2 O, Zn(Ala) 2 ‚H 2 O, Sr(NO 3 ) 2 , and SrMoO 4 . For all samples the quadrupolar coupling parameters and the isotropic chemical shifts are extracted by numerical simulation and iterative fitting of the spin-echo sideband spectra observed in the experimental QCPMG NMR spectra. These parameters are discussed in light of the crystal structures for the compounds.

Magnitudes and relative orientations of 51V quadrupole coupling and chemical shift tensors have been determined from 51V magic-angle spinning (MAS) NMR spectra at 14.1 T for seven divalent metal pyrovanadates:  α- and β-Mg2V2O7, Ca2V2O7, α-Zn2V2O7, Cd2V2O7, BaCaV2O7, and α-BaZnV2O7. This has been accomplished by least-squares fitting of the integrated spinning sideband intensities observed for the central and satellite transitions employing spectral widths up to 4 MHz. Numerical error analysis of the optimized data reveals that the five NMR parameters characterizing the magnitudes of the quadrupole coupling and chemical shift tensors are obtained with high precision while somewhat larger error limits are observed for the three Euler angles, describing the relative orientation of the two tensors. The optimized data exhibit a significantly higher precision when compared to earlier reported parameters for some of the pyrovanadates, determined from 51V static-powder or MAS NMR of the central transition only. The 51V chemical shift parameters indicate that the different conformations for the V2O7 4- ion in thortveitite-type and dichromate-type pyrovanadates can be distinguished by the sign for the chemical shift anisotropy (δσ = δiso − δ zz ), negative and positive, respectively. A linear correlation is observed between the principal elements for the 51V quadrupole coupling tensors and calculated electric field gradient tensor elements, obtained from point−monopole calculations. This correlation is used to assign the NMR parameters for the two different crystallographic 51V sites in the asymmetric units for α- and β-Mg2V2O7, Ca2V2O7, BaCaV2O7, and α-BaZnV2O7.

11B chemical shift anisotropies (CSAs) have been obtained for tetrahedral and trigonal boron sites in tetraphenyl borates, datolite (CaBSiO4(OH)), danburite (CaB2Si2O8), colemanite (CaB3O4(OH)3·H2O), borax (Na2B4O7·10H2O), and Li2B4O7 from solid-state 11B NMR spectra recorded at 14.1 T. These parameters along with 11B quadrupole couplings and the relative orientation of the quadrupole coupling and CSA tensors have been determined from either the manifold of spinning sidebands observed for the satellite transitions in 11B MAS NMR spectra or single-crystal NMR spectra of the satellite transitions. Furthermore, the potential of the MQMAS experiment for determination of small 11B CSAs is illustrated for the trigonal boron site in Li2B4O7. The 11B single-crystal NMR spectra of the satellite transitions are strongly dominated by the first-order quadrupolar interaction, which may prevent a direct determination of small CSAs. However, an improved precision of the CSA parameters and the Euler angles, describing the relative orientation of the CSA and quadrupole coupling tensors, are achieved from analysis of rotation plots for the sum frequencies of the m = 1/2 ↔ m = 3/2 and m = −/2 ↔ m = −3/2 transitions, which are influenced only by the first-order CSA and the second-order quadrupolar interactions. The 11B CSA parameters determined in this work show that tetrahedrally coordinated boron in borates possess shift anisotropies (δσ = δiso − δ zz ) of magnitude |δσ| less than 10 ppm.