(Figure ). The intensity ratio of the two resonances reflects the reaction stoichiometry and the degree of condensation, DC (Figure ). P MAS NMR spectra of products 12-15 (Figure ) are dominated by a resonance at 75 ppm, assigned to the intended TEPO-Al(O-)3 site. In the spectra of products 12 and 13, a minor resonance at 55 ppm was assigned to uncoordinated TEPO. Additionally, the spectra of 1D Al MAS NMR analysis Al{ 1 H} MAS NMR characterizations (Figure ) of products 1-15 showed broad asymmetric features with increasing linewidth in the order: TEPO < Et 3 N < py < THF. Single quadrupolar nucleus line shapes did not yield good fits to the observed features, hinting at the presence of multiple overlapped resonances and preventing direct extraction of the spectroscopic parameters. Product 16 showed a much narrower feature with two maxima at 47 and 52 ppm, allowing for a confident assignment as 4-coordinated Al species. Most notably, the observed line shapes are more complex (16) and much broader (1-15) than those previously reported for the corresponding products. This is attributed to the broader-band excitation used in this work and demonstrates the trickiness involved in the characterization of low-symmetry Al species by Al NMR techniques.