Nuclear Quadrupole Coupling Constants for N₂O: Experiment and Theory

Abstract

The nuclear quadrupole coupling constants (NQCCs) for the nitrogen and oxygen nuclei in N(2)O have been determined using a variety of computational methods (MP2, QCISD, DFT with B3LYP, PBE0, and B3PW91 functionals, CCSD, CCSD(T), CASSCF, and MRCI) combined with correlation-consistent basis sets. When compared to the available experimental determinations, the results demonstrate that only CCSD(T) and MRCI methods are capable of accurately predicting the NQCCs of the central and terminal nitrogen atoms. The spin-rotation and magnetic shielding tensors have also been determined and compared to experimental measurements where available. (14)N and (17)O NMR relaxation data for N(2)O in the gas phase and a variety of solvents is reported. The increase in the ratio of (14)N spin-lattice relaxation times in solvent for the central and terminal nitrogens supports previous reports of the modification of the electric field gradients at these nuclei in van der Waals complexes. Ab initio computations for the linear FH···N(2)O complex confirm the large change in EFGs imposed by a single perturber.

Versatile pulse sequence device to conserve hyperpolarization for NMR and MRI studies

“…The relaxation of N 2 O is substantially shortened (< 1s) (22) in the gas phase due to the spin rotation interaction acting over long coherence times. To reduce polarization loss, it was necessary to minimize the both the pressure of the sample in the gas phase and the amount of time spent in the gas phase due to dynamic equilibria of the dissolved and gaseous phases after dissolution.…”

17o NMR

“…In the same paper, they also present several DFT calculations of the EFG for several small and medium-size molecules, including also transition metal complexes. In the same spirit of the high-level benchmark calculations of the shielding constants in small molecules, Brown and Wasylishen 140 have carried out carried out a detailed experimental and computational study of the nuclear quadrupole coupling constants in N 2 O.…”

“…Both papers 139,140 are recommended to anyone looking for guidelines on the quantitative performance of different methods.…”