Nuclear Magnetic Shielding and Spin−Spin Coupling of 1,2-13C-Enriched Acetylene in Gaseous Mixtures with Xenon and Carbon Dioxide

Abstract

13C and 1H NMR spectra have been measured for 1,2-13C-acetylene at low density in binary mixtures with xenon and carbon dioxide gases as the solvents. It was found that both the chemical shifts and the 1J(CC) coupling constant of 13C2H2 were linearly dependent on the solvent density. The appropriate NMR parameters for an isolated 13C2H2 molecule were determined, together with the coefficients responsible for the solute−solvent molecular interactions. The 13C NMR measurements were extended to solutions of 1,2-13C-acetylene in liquid solvents. All of the 13C gas-to-solution shifts were found to be positive (deshielding effects), and the 1J(CC) coupling constant in liquid acetone was diminished by more than 5% in comparison with the value of 174.78 Hz observed in the gas phase.