O-17 NUCLEAR-QUADRUPOLE DOUBLE-RESONANCE SPECTROSCOPY .1. INTRODUCTION - RESULTS FOR ORGANIC CARBONYL-COMPOUNDS

The pure nuclear quadrupole resonance (NQR) spectra of in 17O natural abundance in 23 subitances containing carbonyl groups arc reported. The spcctra were obtained on powdered solids at 77 K, using the double resonance field cycling technique pioneered by Hahn and co-workers. The substances studied include C6H5C(O)X (X = F. CI. Br, CN).substituted benZ-aldehydes, phenyl benzoate, several acid anhydrides, phthalimide. KHCOj. NaHCO3. sodium formate, andpotassium acid phthalatc. An analysis of the carbonyl oxygen data in terms of a simple Townes-Dailey model shows that variation in carbon-oxygen π bond character among the compounds is ihe major source of variations in quadrupole coupling constant and asymmetry parameter. The atomic orbital populations on oxygen deduced from the NQR data arc in accord with the limitedphysical data and theoretical results available for comparisons. © 1979, American Chemical Society. All rights reserved.