Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields

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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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Autores principales: Pagola, Gabriel Ignacio, Caputo, María Cristina, Ferraro, Marta Beatriz
Publicado: 2009
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15499618_v5_n5_p1343_Boyd
http://hdl.handle.net/20.500.12110/paper_15499618_v5_n5_p1343_Boyd
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling paper:paper_15499618_v5_n5_p1343_Boyd2023-06-08T16:21:29Z Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields Pagola, Gabriel Ignacio Caputo, María Cristina Ferraro, Marta Beatriz 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. 2009 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15499618_v5_n5_p1343_Boyd http://hdl.handle.net/20.500.12110/paper_15499618_v5_n5_p1343_Boyd
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection 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.
author Pagola, Gabriel Ignacio
Caputo, María Cristina
Ferraro, Marta Beatriz
spellingShingle Pagola, Gabriel Ignacio
Caputo, María Cristina
Ferraro, Marta Beatriz
Calculation of hypershielding contribution to isotropic nitrogen shielding in strong magnetic fields
author_facet Pagola, Gabriel Ignacio
Caputo, María Cristina
Ferraro, Marta Beatriz
author_sort Pagola, Gabriel Ignacio
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
publishDate 2009
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15499618_v5_n5_p1343_Boyd
http://hdl.handle.net/20.500.12110/paper_15499618_v5_n5_p1343_Boyd
work_keys_str_mv AT pagolagabrielignacio calculationofhypershieldingcontributiontoisotropicnitrogenshieldinginstrongmagneticfields
AT caputomariacristina calculationofhypershieldingcontributiontoisotropicnitrogenshieldinginstrongmagneticfields
AT ferraromartabeatriz calculationofhypershieldingcontributiontoisotropicnitrogenshieldinginstrongmagneticfields
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