Chemical Shift and Second‐Order Quadrupolar Effects in the Solid‐State 133Cs NMR Spectra of [Cs+(Cryptand[2.2.2])]X (X = I−, SCN−·H2O)

摘要

[Cs+(Cryptand[2.2.2])]I? (1; Cryptand[2.2.2] = C222) was characterized via single‐crystal X‐ray diffraction and was shown to crystallize in the monoclinic space group I2/c system with a = 8.9605 (2), b = 23.5073 (5), c = 11.7563 (3) ?, and β = 93.792 (2)°. Stationary and magic angle spinning (MAS) experiments under different magnetic fields allowed for the separation of the chemical shift and quadrupole coupling tensor parameters. Remarkably, MAS spectra showing pure second‐order quadrupole powder patterns at 4.23?T were observed for 133Cs nuclei with small quadrupole moments owing to the large electric field gradients (EFGs) caused by short Cs?O and Cs?N bond distances in the [Cs+(C222)] ions. Stationary NMR powder patterns with a combination of the chemical shifts and second‐order quadrupolar interactions were observed. The EFG and chemical shift tensor components calculated using the atomic coordinate files and Gaussian 09 were reasonably consistent with the experimental values.