Gas-Phase Studies of NMR Shielding and Indirect Spin-Spin Coupling in 13 C-Enriched Ethane and Ethylene

• Published in: Molecules (Basel, Switzerland) Switzerland), 2024-09, Vol.29 (18)
• Main Authors: Wilczek, Marcin, Jackowski, Karol
• Format: Article
• Language: English
• ISSN: 1420-3049

C and H NMR spectra were observed as the function of density in 1,2- C-enriched ethane and ethylene for the pure gaseous compounds and their binary mixtures with xenon and carbon dioxide gases as the solvents. All the chemical shifts and indirect spin-spin couplings were linearly dependent on the solvent density. The appropriate NMR parameters (σ and J) in isolated C H and C H molecules and the coefficients responsible for the binary molecular interactions were determined and compared with previous similar measurements and selected calculated shielding data. The newly obtained C shielding values in the isolated ethane and ethylene molecules suggest visible secondary isotope effects due to the additional carbon-13 atom. All the investigated shielding parameters depend on intermolecular interactions, and the dependence of C shielding is much more marked. In contrast, the indirect spin-spin couplings in C H and C H molecules are almost independent of solvent molecules. Their J values determined in liquids over sixty years ago are generally consistent with the same J parameters in isolated C H and C H molecules.