The resolution of the 29 Si MAS NMR spectrum of ZEO-2 is excellent (Fig. ), indicating four Q 3 Si sites (-94.2, -95.8, -98.6, and -100.4 ppm) spanning a chemical shift range unprecedented for Q 3 in zeolites (more typically centered at around -102±1 ppm) but well within the general Q 3 range in silicates ( ) and seven Q 4 Si sites (from -106.8 to -116.8 ppm), in good agreement with the crystallographic results (4 Q 3 and 5 Q 4 all with the same multiplicity plus 2 Q 4 with half multiplicity, see CIF). 29 Si{ 1 H} CP MAS NMR spectroscopy proves the existence of those four Q 3 Si sites in ZEO-2 (Fig. top), while the 29 Si MAS NMR spectrum of ZEO-3 reveals total condensation (all Si atoms are Q 4 sites with a negligible amount of Q 3 that could be assigned to connectivity defects, as proved by the very low intensity enhancement by cross polarization, Fig. ).