Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields
Hypershielding contributions to magnetic shielding of the nitrogen N nucleus have been evaluated for some nitroso (RNO) and isodiazene (R 1 R 2 NN) compounds in the presence of an external spatially uniform, time-independent magnetic field, accounting for cubic response via Rayleigh-Schrödinger pert...
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todo:paper_15499618_v5_n5_p1343_Boyd2023-10-03T16:23:21Z Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields Boyd, J. Pagola, G.I. Caputo, M.C. Ferraro, M.B. Lazzeretti, P. Hypershielding contributions to magnetic shielding of the nitrogen N nucleus have been evaluated for some nitroso (RNO) and isodiazene (R 1 R 2 NN) compounds in the presence of an external spatially uniform, time-independent magnetic field, accounting for cubic response via Rayleigh-Schrödinger perturbation theory. Numerical estimates have been obtained at the coupled Hartree-Fock level of accuracy within the conventional common-origin approach. Medium-size basis sets of gaugeless (that is, without gauge-including phase factors) Gaussian functions have been employed in a numerical test to show that the isotropic hypershielding contribution τ N B N , τ N = 1/2〈Σ N αβγδ 〉, eqs 2-4 in the text, to average nitrogen shielding in PhNO (τ N ≈ 1.1 × 10 -5 ppm T -2 ), (CH 3 ) 3 CNO (τ N ≈ 2.3 × 10 -5 ppm T -2 ), and (CH 3 ) 2 NN (τ N ≈ 4.4 × 10 -5 ppm T -2 ) are similar and quite large. For 15 N at the highest currently available high-resolution NMR field strength of 22.3 T (ω H /2π = 950 MHz, ω 15N / 2π = 96.3 MHz) the change due to the additional shielding contribution for these compounds is between ∼0.5 and ∼2 Hz to lower frequency (upfield). Employing modern NMR instrumentation, shielding perturbations of this magnitude are, in principle, within detection limits, although instrumental instabilities and other field-dependent shielding phenomena make unambiguous detection at different field strengths difficult. © 2009 American Chemical Society. Fil:Pagola, G.I. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Caputo, M.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Ferraro, M.B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_15499618_v5_n5_p1343_Boyd |
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Universidad de Buenos Aires |
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I-28 |
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R-134 |
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| description |
Hypershielding contributions to magnetic shielding of the nitrogen N nucleus have been evaluated for some nitroso (RNO) and isodiazene (R 1 R 2 NN) compounds in the presence of an external spatially uniform, time-independent magnetic field, accounting for cubic response via Rayleigh-Schrödinger perturbation theory. Numerical estimates have been obtained at the coupled Hartree-Fock level of accuracy within the conventional common-origin approach. Medium-size basis sets of gaugeless (that is, without gauge-including phase factors) Gaussian functions have been employed in a numerical test to show that the isotropic hypershielding contribution τ N B N , τ N = 1/2〈Σ N αβγδ 〉, eqs 2-4 in the text, to average nitrogen shielding in PhNO (τ N ≈ 1.1 × 10 -5 ppm T -2 ), (CH 3 ) 3 CNO (τ N ≈ 2.3 × 10 -5 ppm T -2 ), and (CH 3 ) 2 NN (τ N ≈ 4.4 × 10 -5 ppm T -2 ) are similar and quite large. For 15 N at the highest currently available high-resolution NMR field strength of 22.3 T (ω H /2π = 950 MHz, ω 15N / 2π = 96.3 MHz) the change due to the additional shielding contribution for these compounds is between ∼0.5 and ∼2 Hz to lower frequency (upfield). Employing modern NMR instrumentation, shielding perturbations of this magnitude are, in principle, within detection limits, although instrumental instabilities and other field-dependent shielding phenomena make unambiguous detection at different field strengths difficult. © 2009 American Chemical Society. |
| format |
JOUR |
| author |
Boyd, J. Pagola, G.I. Caputo, M.C. Ferraro, M.B. Lazzeretti, P. |
| spellingShingle |
Boyd, J. Pagola, G.I. Caputo, M.C. Ferraro, M.B. Lazzeretti, P. Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields |
| author_facet |
Boyd, J. Pagola, G.I. Caputo, M.C. Ferraro, M.B. Lazzeretti, P. |
| author_sort |
Boyd, J. |
| title |
Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields |
| title_short |
Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields |
| title_full |
Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields |
| title_fullStr |
Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields |
| title_full_unstemmed |
Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields |
| title_sort |
calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields |
| url |
http://hdl.handle.net/20.500.12110/paper_15499618_v5_n5_p1343_Boyd |
| work_keys_str_mv |
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| _version_ |
1807324138586505216 |