Proton shielding function for hydrogen chloride |
| |
Authors: | WT Raynes BP Chadburn |
| |
Institution: | Department of Chemistry , University of Sheffield , S3 7HF |
| |
Abstract: | For a diatomic molecule the nuclear shielding constant σ(ξ) of either nucleus can be expanded as a power series in the relative displacement from equilibrium ξ. Thus the nuclear shielding function is where ξ=(r-r e)/r e with r the actual bond length and r e the equilibrium bond length. The σe (i) are molecular parameters. By experimental observation of the temperature dependence of the proton magnetic shielding of hydrogen chloride gas it is possible, after allowing for intermolecular effects, to obtain the values σe (0)=32·48 (±0·33) p.p.m. and σe (1)=-100 (±24) p.p.m. for the coefficients of the proton shielding function. Using this data it is possible to show that the isotope shift between H37Cl and H35Cl is about 0·001 p.p.m. By a comparison with earlier results for molecular hydrogen it would appear that in some instances differences in vibrational and rotational averaging may alter chemical shifts between different compounds by amounts considerably larger than the experimental error in chemical shift measurement. |
| |
Keywords: | |
|
|