Nuclear quadrupole resonance Zeeman study of 137Ba in barium chloride dihydrate

Solid-State 137Ba NMR Spectroscopy: An Experimental and Theoretical Investigation of 137Ba Electric Field Gradient Tensors and Their Relation to Structure and Symmetry

“…Simulations of the spectra (Figure ) reveal a single barium site, in agreement with the crystal structure . The C Q value is similar to that obtained from NQR; however, the η Q value of 0.78(14) is different. , The η Q value obtained from our NMR experiments is likely more accurate, since the previously reported η Q value was estimated from calculations and quadrupolar parameters of analogous systems, and not directly measured in the NQR experiments (NQR experiments on spin-3/2 nuclei do not readily permit determination of η Q , unless special techniques are applied). , The barium atom is coordinated to four oxygen and five chlorine atoms (Scheme d), with Ba−O bond distances varying from 2.844 to 2.887 Å and Ba−Cl distances varying from 3.131 to 3.340 Å . The chlorine and oxygen atoms are arranged such that no simple geometrical assignments of shape can be made; in fact, the arrangement of atoms has been described “approximately as a square antiprism with one square face enlarged to accommodate the fifth Cl − ion” .…”

“…54 Dihydrate and Anhydrous Forms of Barium Chloride. The 137 Ba quadrupolar parameters of barium chloride dihydrate were previously obtained from NQR experiments on single crystal 66 and polycrystalline samples. 67 In the former case, the extraction of the quadrupolar parameters was complicated by crystal twinning, while, in the latter case, a very large amount of crystalline sample was used (i.e., 25 g) in order to obtain the signal (again, this can be inconvenient and impractical in many situations where sample sizes are limited).…”

“…56 The C Q value is similar to that obtained from NQR; however, the η Q value of 0.78 (14) is different. 66,67 The η Q value obtained from our NMR experiments is likely more accurate, since the previously reported η Q value was estimated from calculations and quadrupolar parameters of analogous systems, and not directly measured in the NQR experiments (NQR experiments on spin-3/2 nuclei do not readily permit determination of η Q , 68 unless special techniques are applied). 69,70 The barium atom is coordinated to four oxygen and five chlorine atoms (Scheme 1d), with Ba-O bond distances varying from 2.844 to 2.887 Å and Ba-Cl distances varying from 3.131 to 3.340 Å.…”

“…η Q ) 0.48 indicates that V 33 is the distinct component of the EFG tensor, which is likely oriented along the 2-fold rotational axis of the molecule, which includes the lone Ba-OH 2 bond (Scheme 1c). Ba quadrupolar parameters of barium chloride dihydrate were previously obtained from NQR experiments on single crystal 66 and polycrystalline samples. 67 In the former case, the extraction 137 Ba static SSNMR spectra of barium carbonate at two different magnetic field strengths.…”