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 (σ_p)(ΔE), both depend on the imbalance of electronic charge around nitrogen. A similar correlation is found between the asymmetry parameter η and (σ_p)(ΔE), and there is even some correlation of η and σ_p. Nqcc/δ correlations have previously been predicted (for ³⁵Cl), but have been difficult to establish because of lack of information on the excitation energies.