GIAO-NMR

Fluorinated Position (Compound) A Er (kcal/mol) Gas Phase (Aqueous Phase) qFb (AqF)b GIAO-NMR S,9F (A8,9F) (PPm) C-F Bond Length (Angstroms)... 

According to a semiempirical study by Malar, the different polyphospholide anions have 86—101% aromaticities of that of the cyclopentadienide anion. Chesnut and Quin reported on the basis of GIAO NMR calculations using a triple-valence quality basis set that the phospholide anion s aromaticity is 63% that of the cyclopentadienide anion. The aromatic stabilization energy (ASE) obtained by Schley-er et al. from eq 2 (X = P ) was 90% that of the cyclopentadienide anion. 

Subsequently, DFT methods (B3LYP functional ) were employed to compute (1) natural charges from which changes in charges are mapped out for comparison with the NMR-based conclusions, (2) GIAO-NMR to predict the chemical shifts for comparison with the experimental results, and (3) nuclear-independent chemical shift (NICS) in order to evaluate relative aromaticity in different rings. Finally, solvent effects were estimated by the polarized continuum model (PCM). In selected cases, parallel DNA-binding studies (with MCF-7 human mammary... 

Computed GIAO-NMR chemical shifts were compared with the experimental data when available, and the optimized geometries were compared with the X-ray data if known. The lowest energy annulenium cation derived from 76 and 77 (both cis) was formed by protonation at C-1, and this was in concert with experimental observation of 76H" in superacid media. " The resulting annulenium ions were less delocalized than those via 74 and 75. DFT and stable ion study were also in concert regarding the protonation of 78. The availability of X-ray structures and stable ion NMR data for the dieations and dianions of 78 and 79 enabled comparison with the DFT-optimized structures and GIAO-NMR shifts. 

Table 2. Calculated shieldings for different coordination number Si hydroxides (6-31G GIAO NMR and optimized geometries) compared with experimental values (ref. 18).

Table 7. Experimental and calculated N NMR shieldings in models for P3N5 (6-31G optimized geometries and 6-31G or 6-311(2d,p) GIAO NMR).

Geometry, energy, energetics for dissociation, GIAO NMR chemical shifts... 

Smith, S. G. Goodman, J. M. Assigning the stereochemistry of pairs of diastereoiso-mers using GIAO NMR shift calculation, J. Org. Chem. 2009, 74,4597-4607. 

NMR shifts of protons in Figure 13.13 were assigned by GIAO NMR calculation at the B3LYP/6-31G level of density functional theory. 

Wolff, SK, Ziegler T (1998) Calculation of DFT-GIAO NMR shifts with the inclusion of spin-orbit... 

B-signals , Computational studies ofnttfo-[C4B7Hn] carboranes and nido-8-vertex boranes and carboranes , Applications of IGLO/GIAO NMR computations of carborane systems products of trimethylamine/c/o o-carborane reactions carborane C chemical shifts and Extension of the borane-carbocation continuum to cage systems . ... 

When only the NMR spectrum, but little or no structural information, is available for a given compound, the application of the ab initio/lGLO (or GIAO)/NMR method involves the following steps ... 

The success of the ab i/iirio/IGLO (or GIAO)/NMR method for carbocations has prompted similar studies for another class of electron deficient compounds, namely for the boranes and for hetero-substituted derivatives thereof. In contrast to the... 

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