17O and 1H NMR spectral parameters in isolated water molecules

• Published in: Physical chemistry chemical physics : PCCP 2018-01, Vol.2 (35), p.22468-22476
• Main Authors: Makulski, W odzimierz, Wilczek, Marcin, Jackowski, Karol
• Format: Article
• Language: English
• Subjects: Buckminsterfullerene; Chemical equilibrium; Coupling; Coupling (molecular); Density; Dipole moments; Fullerenes; Isotope effect; Magnetic dipoles; Magnetic shielding; Mathematical analysis; NMR; Nuclear magnetic resonance; Nuclei (nuclear physics); Organic chemistry; Oxygen enrichment; Parameters; Water chemistry
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c8cp01748d

Small amounts of water enriched in oxygen-17 were studied by 17 O and 1 H NMR in binary gaseous mixtures with Xe, Kr, CHF 3 and CH 3 F and CO 2 . The distinct linear dependences of 17 O and 1 H chemical shifts and 1 J ( 17 O, 1 H) spin-spin coupling on the density of every gas solvent were measured. After the extrapolation of experimental results to zero density the relevant parameters in the isolated H 2 17 O molecule were determined. The same procedure was applied for H 2 16 O when its proton chemical shift was analyzed but the secondary isotope effect in the 1 H shielding of H 2 17 O and H 2 16 O molecules was too small for detection. As shown, all the intermolecular effects in nuclear magnetic shielding are negative and these effects are more significant for 17 O nuclei than for protons. It is consistent with the appropriate gas-to-liquid shifts of water which also indicate deshielding effects for both the investigated nuclei. On the other hand, the 1 J 0 ( 17 O, 1 H) coupling constant in H 2 17 O, which is completely free from intermolecular interactions, considerably differs from the 1 J ( 17 O, 1 H) experimental values obtained for water in liquid solutions. The present experimental data of the isolated H 2 17 O molecule are compared with selected results of shielding and spin-spin coupling calculations available from the literature and with the recent experimental data for a water molecule encapsulated in the C 60 fullerene. Additionally, on the basis of actual results the magnetic dipole moment of the 17 O nucleus is revalued for greater accuracy. Small amounts of water were studied by 17 O and 1 H NMR in binary gaseous mixtures with Xe, Kr, CHF 3 and CH 3 F and CO 2 .