IMIT   21220
INSTITUTO DE MODELADO E INNOVACION TECNOLOGICA
Unidad Ejecutora - UE
artículos
Título:
Nuclear charge-distribution effects on the NMR spectroscopy parameters
Autor/es:
ALEJANDRO MALDONADO; CARLOS A. GIMENEZ; GUSTAVO A. AUCAR
Revista:
JOURNAL OF CHEMICAL PHYSICS
Editorial:
AMER INST PHYSICS
Referencias:
Lugar: New York; Año: 2012 vol. 136 p. 224110 - 224120
ISSN:
0021-9606
Resumen:
We present here a systematic study about the influence of the size and type of nuclear chargedistribution models (Gaussian and point-like) on the NMR spectroscopic parameters, the nuclear magnetic shielding σ and the indirect nuclear spin J-coupling. We found that relativistic effects largely enhance the nuclear charge-distribution effects (NChDE) on those parameters being them quite sensitive to the nuclear model adopted for calculations. Results for two rare gas atoms (Kr,Rn) and few molecular systems like HX, (X = Br, I, At), CH4, SnH4, SnIH3, SnI2H2, and PbIH3 are presented. J-couplings are more sensitive than shieldings in both, relativistic and non-relativistic (NR) regimes. The highest effect (close to 11% of variation in relativistic calculations with that two different nuclear models) is observed for J(Pb–I) in PbIH3. A similar effect is found for J(Pb–H) in the same molecule, close to 9%. The NChDE for σ(Sn) in SnI4−nHn with n = 1, 2 is as large as few ppm (between 3 and 8.56 ppm). For J(Sn–H) in this set of molecules, it goes from 37 Hz for SnH4 to 54 Hz for SnI2H2. Furthermore, we found that the vicinal NChDE is very small though not zero. For 1J(Sn–H) in SnIH3, the NChDE of iodine is close to 2 Hz (0.1%). We also studied the NChDE on the ground state electronic energies of atoms and molecules. We found that these effects are only important within the relativistic regime but not within the NR one. They are in good agreement with previous works