Solid-state NMR studies of 17O-enriched pyrophosphates

For the first time, 17O NMR studies were performed on 17O-enriched crystalline pyrophosphates (magnesium-, sodium- and barium-pyrophosphate) by means of triple-quantum magic-angle spinning (3QMAS) and double-rotation (DOR) in the high external field of 17.6 T. Oxygen atoms in bridging positions (P-OB-P) exhibit a significant higher quadrupole coupling constant compared to oxygen atoms in terminal positions (P-OT). With increasing cationic radius a higher value of the chemical shift of the terminal oxygen atoms is observed.