Multinuclear NMR spectroscopy of ethanol isotopic forms in the liquid and gas phase

Absolute 13C nuclear magnetic shielding of simple isolated molecules from gas phase measurements

“…In this work, much attention was paid to the carbon oxide molecule and its 13 C spectra. It is now possible to note the isotope effects observed on the 13 C nucleus connected with oxygen isotopic substitution 16 O/ 17 O/ 18 O. This effect was previously observed by Wasylishen 55 .022(0.0229) ppm in chloroform.…”

“…Our new experimental results collected in the series of experimental investigations 3–24 can be compared with those present in the literature to date. For this purpose the experimental results of Jameson 36 were recalculated against the new σ 0 ( 13 CO) = 0.80(90) ppm value and correlated with our shielding constants taken from Table 2.…”

“…Absolute shielding scales refer to the hypothetical ''bare'' nuclei, namely 13 C +6 and 17 O +8 . 13 C 16 O and 12 C 17 O, taken as isolated species, are the primary reference molecules in this approach. 1 Isolated molecule means that its physical properties are specified for the gaseous state by extrapolation to the zeropressure limit.…”

“…The final results were published in a series of papers. 3–24 Several brand-new results for 28 chemical compounds were also included. Nonetheless, it is important that all measurements were carried out under similar standardised conditions.…”

“…Nuclear magnetic shielding was then calculated as the sum of two parts (s e = s d + s p ): diamagnetic contribution s d = 327.16 ppm (theoretical) and paramagnetic contribution s p = À324.2 ppm (experimental). The last value arises from the spinrotation constant in the13 C16 O molecule measured from the molecular beam experiment C I = 32.73(12) kHz. The final shielding constant was upgraded by the ro-vibration correction at 300 K s ZPV = À2.0 ppm 36 with error bar AE1.2 ppm.…”