Nitrogen nuclear magnetic resonance spectroscopy. Part 6.—Correlation of 14N chemical shifts and nuclear quadrupole coupling constants in nitroso (nitrosyl) compounds
Abstract
For nitrogen in XNO (nitroso and nitrosyl) compounds, a roughly linear relationship is demonstrated between the nuclear quadrupole coupling constant (nqcc) and the product of the nuclear magnetic shielding constant and an excitation energy ΔE, which can be approximated by the energy of the n→π* band in the u.v.—visible spectrum; since the nqcc and (δ)(ΔE), or rather (σp)(ΔE), both depend on the imbalance of electronic charge around nitrogen. A similar correlation is found between the asymmetry parameter η and (σp)(ΔE), and there is even some correlation of η and σp. Nqcc/δ correlations have previously been predicted (for 35Cl), but have been difficult to establish because of lack of information on the excitation energies.