Application of the ab initio/IGLO/NMR method to the structure confirmation of the [.mu.5,6-BHNR2-nido-2,4-C2B4H6]- ion intermediate observed during the interaction of closo-2,4-C2B5H7 with LiNR2

Onak, Thomas; Tseng, James; Diaz, Martin; Tran, Dan; Arias, Joachin; Herrera, Sergio; Brown, Diane R.

doi:10.1021/ic00056a024

Cited by 42 publications

(29 citation statements)

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“…We used the triple‐zeta basis set plus one polarization function (denoted TZP; from the ADF library) for all atoms. 11 B chemical shifts were calculated relative to B 2 H 6 and converted to the usual BF 3 ⋅ OEt 2 scale by using the experimental δ ( 11 B) value for B 2 H 6 of 16.6 ppm . NMR chemical shifts are given in Table .…”

Section: Methodssupporting

confidence: 87%

Icosahedral Carbaboranes with Peripheral Hydrogen–Chalcogenide Groups: Structures from Gas Electron Diffraction and Chemical Shielding in Solution

Baše

Holub

Fanfrlík

et al. 2019

Chemistry A European J

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Carbaboranes 1,2‐(EH)2‐closo‐1,2‐C2B10H10 (E=S, Se) were prepared, in the case of E=Se for the first time. Their semi‐experimental equilibrium molecular structures were established by the concerted use of quantum‐chemical calculations and gas electron diffraction. A method was developed and implemented to quantify the contribution of experimental data to each refined structural parameter. The accuracy of the experimental structures and those calculated at the MP2 level of theory were gauged by comparison of experimental 11B NMR chemical shifts with quantum‐chemically computed values; the inclusion of electron correlation (GIAO‐MP2) provided superior results. For the purpose of geometrical prediction, the remaining group 16 elements were considered, and the icosahedral structures for E=O and Te were also computed; for E=O the same theoretical approach was used as for E=S, and for E=Te a description similar to that for E=Se was employed.

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Section: Methodssupporting

confidence: 87%

Icosahedral Carbaboranes with Peripheral Hydrogen–Chalcogenide Groups: Structures from Gas Electron Diffraction and Chemical Shielding in Solution

Baše

Holub

Fanfrlík

et al. 2019

Chemistry A European J

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“…The calculated 13 C NMR chemical shifts of the compounds reported here agree very well with the available experimental values. Isotropic 13 C NMR shieldings from GIAO calculations account well for relative chemical shifts even with relatively modest basis sets.…”

Section: Discussionsupporting

confidence: 85%

“…The prediction of NMR chemical shifts from quantum mechanical methods has undergone major advancements within the last decade, including solutions to the gauge dependence of the chemical shift [1,2], improvements in the basis set and the extension of higher levels of theory including density functional techniques [3,4]. DFT calculations are now attainable and accurate enough to be useful exploring the relationship between chemical shift and molecular structure [5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Correlation Between Experimental and DFT/GIAO Computed 13C NMR Chemical Shifts of Organic Compounds. Effects of Asymmetry

Borkowski¹

2012

TONPJ

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The experimental 13 C chemical shifts of five different series of organic compounds are compared with predicted 13 C NMR chemical shifts obtained via empirically scaled GIAO shieldings. Our results indicate that the inclusion of a scaling factor allow to obtain an excellent correlation between δ calc and δ exp. Although the inclusion of asymmetry improves this correlation, such enhancement was not observed for all the 54 tested compounds. We found  RMS , a parameter related with the structural feature of the whole molecule, which could indicate the benefits of including asymmetry in these calculations.

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“…[7][8][9] The methodology established for these classes of compounds, that is, optimization of geometries at correlated ab initio levels and chemical shift computations at IGLO-SCF, GIAO-SCF, or GIAO-MP2 levels, is being routinely applied as an independent tool for characterization of newly synthesized borane and carbaborane derivatives, [9] and the credibility of structural assigments based on this method has been attested to "rival that of X-ray crystallography". [10] These assignments rely on an accuracy of about 2-3 ppm that can be achieved for the computed 11 B chemical shifts. To approach similar accuracy for molecules containing transition-metal atoms, it may be necessary to go beyond these low ab initio levels (Hartree-Fock or MP2) in the chemicalshift computation.…”

mentioning

confidence: 99%

Computational Study of Structures and Properties of Metallaboranes: Cobalt Bis(dicarbollide)

Bühl

Hnyk

Macháček

2005

Chemistry A European J

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A density functional study at the BP86/AE1 level is presented for the cobalt bis(dicarbollide) ion [3-Co-(1,2-C2B9H11)2]- (1) and selected isomers and rotamers thereof. Rotation of the two dicarbollide moieties with respect to each other is facile, as judged by the small energetic separation of the three rotamers located (within 11 kJ mol(-1)) and by the low barriers for their interconversion (at most 41 kJ mol(-1)). Among the isomers differing in carbon atom positions that contain two equivalent dicarbollide ligands, the 1,7 ("carbon apart") form [2-Co-(1,7-C2B9H11)2]- is the most stable, 121 kJ mol(-1) below 1. The electronic structure of 1 is characterized in terms of molecular orbitals, population analysis, and excitation energies from time-dependent density functional theory, relevant to UV/Vis spectroscopy. Experimental 11B NMR chemical shifts of 1 are reproduced to better than 5 ppm at the GIAO-B3LYP/II' level, and the computed delta(11B) values are only little affected by rotational averaging or the presence of a polarizable continuum. Larger such effects are found for the as-yet unknown 59Co chemical shift, for which a value in the range between -1800 and -2400 ppm is predicted. Even though the accuracy achieved for the theoretical delta(11B) values is somewhat lower than that for heteroboranes at conventional ab initio levels, the level of density functional employed can afford qualitatively reliable chemical shifts, which can be useful in assignments and structural refinements of heteroboranes containing transition metal.

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Application of the ab initio/IGLO/NMR method to the structure confirmation of the [.mu.5,6-BHNR2-nido-2,4-C2B4H6]- ion intermediate observed during the interaction of closo-2,4-C2B5H7 with LiNR2

Cited by 42 publications

References 0 publications

Icosahedral Carbaboranes with Peripheral Hydrogen–Chalcogenide Groups: Structures from Gas Electron Diffraction and Chemical Shielding in Solution

Icosahedral Carbaboranes with Peripheral Hydrogen–Chalcogenide Groups: Structures from Gas Electron Diffraction and Chemical Shielding in Solution

Correlation Between Experimental and DFT/GIAO Computed 13C NMR Chemical Shifts of Organic Compounds. Effects of Asymmetry

Computational Study of Structures and Properties of Metallaboranes: Cobalt Bis(dicarbollide)

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