Nuclear magnetic shielding and spin-spin coupling of 1,2-13C-enriched acetylene in gaseous mixtures with xenon and carbon dioxide

C-13 and H-1 NMR spectra have been measured for 1,2-C-13-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 (11)J(CC) coupling constant of (C2H2)-C-13 were linearly dependent on the solvent density. The appropriate NMR parameters for an isolated (C2H2)-C-13 molecule were determined, together with the coefficients responsible for the solute-solvent molecular interactions. The C-13 NMR measurements were extended to solutions of 1,2-C-13-acetylene in liquid solvents. All of the C-13 gas-to-solution shifts were found to be positive (deshielding effects), and the (1)J(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.