Nuclear magnetic shielding and spin-spin coupling of 1,2-C-13-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 d ensity in binary mixtures with xenon and carbon dioxide gases as the solven ts. It was found that both the chemical shifts and the (11)J(CC) coupling c onstant of (C2H2)-C-13 were linearly dependent on the solvent density. The appropriate NMR parameters for an isolated (C2H2)-C-13 molecule were determ ined, together with the coefficients responsible for the solute-solvent mol ecular interactions. The C-13 NMR measurements were extended to solutions o f 1,2-C-13-acetylene in liquid solvents. All of the C-13 gas-to-solution sh ifts were found to be positive (deshielding effects), and the (1)J(CC) coup ling constant in liquid acetone was diminished by more than 5% in compariso n with the value of 174.78 Hz observed in the gas phase.