HIGH-RESOLUTION AL-27 SOLID-STATE MAGIC-ANGLE SAMPLE-SPINNING NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPIC STUDY OF ALCL3-TETRAHYDROFURAN COMPLEXES

We have obtained27A1 solid-state nuclear magnetic resonance (NMR) spectra of several A1C13-THF complexes, using “magicangle” sample-spinning (MASS) NMR at high field. Our results suggest that the isotropic chemical shifts (δj) occur in relatively well defined regions for 4-, 5-, and 6-coordinate species (AIC14−, ~103 ppm; A1C13·THF, ~99 ppm; trans-AlCl3·2THF, ~60 ppm; trans-[AlCl2(THF)4]+, ~ 14 ppm), as found previously with aluminum oxo compounds. We also find that theoretically calculated average nuclear quadrupole coupling constants (e2qQ/h) (/ran5-[AlCl2(THF)4]+, ~6.3 MHz; trans-AlCl3·2THF, ~4.6 MHz; A1C13-THF, ~3.0 MHz; A1C14−, 0 MHz) are in good accord with experimentally determined nuclear quadrupole coupling constants, determined from computer simulations of the MASS NMR spectra (trans-[AlCl2(THF)4]+, 6.4 MHz; trans-AlCl3·2THF, 4.9 MHz; A1C13·THF, 4.7 MHz; A1C14−, 0.3 MHz). Both 27Al δjand e2qQ/h determinations appear to be useful as probes of structure in these systems, and thus offer a facile means of monitoring various solid-state reactions. © 1990, American Chemical Society. All rights reserved.