Comparative multinuclear ( 35 Cl, 79 Br, 81 Br, 127 I and 17 O) magnetic resonance study of the perhalate anions XO 4 − (X Cl, Br or I) in acetonitrile solution
1995; Wiley; Volume: 33; Issue: 1 Linguagem: Inglês
10.1002/mrc.1260330109
ISSN1097-458X
AutoresM. F. A. DOVE, Jeremy C. P. Sanders, Evan H. Appelman,
Tópico(s)Molecular spectroscopy and chirality
ResumoAbstract The NMR spectra ( 35 Cl, 79 Br, 81 Br, 127 I and 17 O) of the tetrahedral perhalate anions XO 4 − (X Cl, Br and I) were compared for the first time in acetonitrile solution, a medium in which the resonances are relatively sharp and in which no oxygen exchange occurs. Relaxation studies of the quadrupolar nuclei in these solutions at 24°C are reported and show that excellent spectra may be obtained at 0.1 M concentration; thus the observation of separate resonances for Cl 16 O 4 − and Cl 18 O 16 O 3 − represents the first reported instance of a 35 Cl secondary isotopic shift [ 1 Δ 35 Cl( 18.16 O) = ‐0.090 ppm]. Enrichment with 17 O of all three ions was carried out and the 1 J( 127 I, 17 O) coupling constant (489 Hz) has been observed for the first time. The chemical shifts and coupling constants are discussed, especially in connection with the anomalous properties of the perbromate ion. Halogen chemical shifts for BrO 3 F, IF 7 and IF 6 + AsF 6 − are reported for the first time.
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