| Popis: |
Nuclear quadrupole resonance spectra of deuterium are reported for anhydrous 2-imidazolidone (ethylene urea), its hemihydrate, phthalimide, and benzamide at 77 K. Imidazolidone-(N,N′)-d2 shows a single deuteron site per asymmetric unit, with e2qQ/h = 208.0 kHz and η = 15.4%. The hemihydrate, imidazolidone -(N1,N3)-d 2 · 1 2 D20 shows two ND sites and one OD site per asymmetric unit: N1-D1 with e2qQ/h = 196.3 kHz, η = 16.8%, N3D3 with e2qQ/h = 204.9 kHz and η = 15.9%, OW-DW with e2qQ/h = 228.2 kHz and 11.4% nonaxiality. These values and multiplicities are consistent with the subsequently determined room-temperature X-ray structures. Dipolar fine structure was observed for the D20 site, with DD distance = 1.586 A and the field gradient tensor at deuterium is oriented with its principal z axis parallel to the OD bond and its principal y axis perpendicular to the D0D plane. Incomplete dipolar structure was also observed for benzamide-(N)-d2, the interaction considerably diminished by the crystallographic inequivalence of the two deuterons of the −ND2 group. The coupling constants and asymmetry parameters for the two crystallographic sites in this compound are 193.0 kHz, 18.1 % (site H6) and 211.1 kHz, 15.9% (site H7). In accord with the known structure of phthalimide-(N)-d2, a single site is observed with e2qQ/h = 187.6 kHz, η = 16.4%. |
