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Gester RM, Georg HC, Canuto S, Caputo MC, Provasi PF. NMR Chemical Shielding and Spin−Spin Coupling Constants of Liquid NH3: A Systematic Investigation using the Sequential QM/MM Method. J Phys Chem A 2009; 113:14936-42. [DOI: 10.1021/jp9050484] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rodrigo M. Gester
- Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970, São Paulo, SP, Brazil, Instituto de Física, Universidade Federal de Goiás, CP 131, 74001-970, Goiânia, GO, Brazil, Department of Physics, University of Buenos Aires, Ciudad Universitaria 1400 - Buenos Aires, Argentina, and I-MIT (CONICET) and Department of Physics, Northeastern University, Av. Libertad 5500, W 3404 AAS - Corrientes, Argentina
| | - Herbert C. Georg
- Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970, São Paulo, SP, Brazil, Instituto de Física, Universidade Federal de Goiás, CP 131, 74001-970, Goiânia, GO, Brazil, Department of Physics, University of Buenos Aires, Ciudad Universitaria 1400 - Buenos Aires, Argentina, and I-MIT (CONICET) and Department of Physics, Northeastern University, Av. Libertad 5500, W 3404 AAS - Corrientes, Argentina
| | - Sylvio Canuto
- Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970, São Paulo, SP, Brazil, Instituto de Física, Universidade Federal de Goiás, CP 131, 74001-970, Goiânia, GO, Brazil, Department of Physics, University of Buenos Aires, Ciudad Universitaria 1400 - Buenos Aires, Argentina, and I-MIT (CONICET) and Department of Physics, Northeastern University, Av. Libertad 5500, W 3404 AAS - Corrientes, Argentina
| | - M. Cristina Caputo
- Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970, São Paulo, SP, Brazil, Instituto de Física, Universidade Federal de Goiás, CP 131, 74001-970, Goiânia, GO, Brazil, Department of Physics, University of Buenos Aires, Ciudad Universitaria 1400 - Buenos Aires, Argentina, and I-MIT (CONICET) and Department of Physics, Northeastern University, Av. Libertad 5500, W 3404 AAS - Corrientes, Argentina
| | - Patricio F. Provasi
- Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970, São Paulo, SP, Brazil, Instituto de Física, Universidade Federal de Goiás, CP 131, 74001-970, Goiânia, GO, Brazil, Department of Physics, University of Buenos Aires, Ciudad Universitaria 1400 - Buenos Aires, Argentina, and I-MIT (CONICET) and Department of Physics, Northeastern University, Av. Libertad 5500, W 3404 AAS - Corrientes, Argentina
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Watson MA, Sałek P, Macak P, Jaszuński M, Helgaker T. The calculation of indirect nuclear spin-spin coupling constants in large molecules. Chemistry 2006; 10:4627-39. [PMID: 15378642 DOI: 10.1002/chem.200306065] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We present calculations of indirect nuclear spin-spin coupling constants in large molecular systems, performed using density functional theory. Such calculations, which have become possible because of the use of linear-scaling techniques in the evaluation of the Coulomb and exchange-correlation contributions to the electronic energy, allow us to study indirect spin-spin couplings in molecules of biological interest, without having to construct artificial model systems. In addition to presenting a statistical analysis of the large number of short-range coupling constants in large molecular systems, we analyse the asymptotic dependence of the indirect nuclear spin-spin coupling constants on the internuclear separation. In particular, we demonstrate that, in a sufficiently large one-electron basis set, the indirect spin-spin coupling constants become proportional to the inverse cube of the internuclear separation, even though the diamagnetic and paramagnetic spin-orbit contributions to the spin-spin coupling constants separately decay as the inverse square of this separation. By contrast, the triplet Fermi contact and spin-dipole contributions to the indirect spin-spin coupling constants decay exponentially and as the inverse cube of the internuclear separation, respectively. Thus, whereas short-range indirect spin-spin coupling constants are usually dominated by the Fermi contact contribution, long-range coupling constants are always dominated by the negative diamagnetic spin-orbit contribution and by the positive paramagnetic spin-orbit contribution, with small spin-dipole and negligible Fermi contact contributions.
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Affiliation(s)
- Mark A Watson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
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Bryce DL, Wasylishen RE. Interpretation of indirect nuclear spin-spin coupling tensors for polyatomic xenon fluorides and group 17 fluorides: results from relativistic density-functional calculations. Inorg Chem 2002; 41:3091-101. [PMID: 12054987 DOI: 10.1021/ic020025u] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Significant improvements have been made recently in the calculation of NMR indirect nuclear spin-spin coupling tensors (J). In particular, the relativistic zeroth-order regular approximation density-functional theory (ZORA-DFT) approach holds great promise for the calculation of spin-spin coupling constants for a variety of chemical systems containing heavy nuclei. In the present work, the ZORA-DFT method is applied to the calculation of the complete reduced coupling tensors, K, for a range of chlorine-, bromine-, iodine-, and xenon-containing species: K(Cl,F) for ClF(2)(+), ClF(3), ClF(4)(+), ClF(5), ClF(6)(-), and ClF(6)(+); K(Br,F) for BrF(3), BrF(6)(-), and BrF(6)(+); K(I,F) for IF(4)(+) and IF(6)(+); K(Xe,F) for XeF(+), XeF(2), XeF(3)(+), XeF(4), XeF(5)(-), XeF(5)(+), and XeF(7)(+). These species represent a wide variety of geometrical bonding arrangements. Agreement between the calculated coupling constants and available experimental data is excellent, and the absolute sign of the coupling constants is provided. It is shown that (1)K(iso) may be positive or negative even within the same molecule, e.g., K(Cl,F)(iso) may be of either sign, depending on the local environment. Periodic trends in (1)K(iso) for isovalent and isostructural molecules are evident. The spin-spin coupling anisotropies, Delta K, and the orientations of the K tensors are also determined. The success of the calculations is a direct result of employing reliable geometries and considering both scalar and spin-orbit relativistic effects. The dependence of K(Cl,F)(iso) and K(Xe,F)(iso) on the local molecular and electronic structure is discussed in terms of the paramagnetic spin-orbit (PSO) and combined Fermi-contact spin-dipolar (FC+SD) coupling mechanisms. The PSO term depends strongly on the number of valence shell electron lone pairs on the central heavy atom, and the FC+SD contribution increases with the Cl[bond]F or Xe[bond]F bond length for a given series of compounds. This interpretation allows for the successful rationalization of the existing experimental data.
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Affiliation(s)
- David L Bryce
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
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Lantto P, Vaara J, Kantola AM, Telkki VV, Schimmelpfennig B, Ruud K, Jokisaari J. Relativistic spin-orbit coupling effects on secondary isotope shifts of (13)C nuclear shielding in CX(2) (X = O, S, Se, Te). J Am Chem Soc 2002; 124:2762-71. [PMID: 11890828 DOI: 10.1021/ja016537+] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rovibrational corrections, temperature dependence, and secondary isotope shifts of the (13)C nuclear shielding in CX(2) (X = O, S, Se, Te) are calculated taking into account the relativistic spin-orbit (SO) interaction. The SO effect is considered for the first time for the secondary isotope shifts. The nuclear shielding hypersurface in terms of nuclear displacements is calculated by using a density-functional theory method. Ab initio multiconfiguration self-consistent field calculations are done at the equilibrium geometry for comparison. (13)C NMR measurements are carried out for CS(2). The calculated results are compared with both present and earlier experimental data on CO(2), CS(2), and CSe(2). The heavy-atom SO effects on the rovibrational corrections of (13)C shielding are shown to be significant. For CSe(2) and CTe(2), reliable prediction of secondary isotope effects and their temperature dependence requires the inclusion of the SO corrections. In particular, earlier discrepancies of theory and experiment for CSe(2) are fully resolved by taking the SO interactions into account.
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Affiliation(s)
- Perttu Lantto
- NMR Research Group, Department of Physical Sciences, P.O. Box 3000, FIN-90014 University of Oulu, Finland
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