IGLO

The individual gauge for localized orbitals (IGLO) and localized orbital... 

The localized quantities of the IGLO results allow separation of the influences of the different bonds, of the inner shells and of the lone pairs on the shielding of the resonance nuclei. It is evident from Table 1 that the SiX bonds with different substituents X do mainly contribute to the chemical shifts. On the other hand, the substituents X have distinct influences on the chemically unchanged parts of the molecules as in system II and on the inner L shell which, on their parts, influence the nuclear shielding, too. 

W. Kutzelnigg, U. Fleischer, M. Schindler, The IGLO-method Ab initio Calculation and Interpretation of NMR Chemical Shifts and Magnetic Susceptibilities, in NMR Basic Principles and Progress, Vol. 23, p. 165 ff., Springer, Berlin 1990. 

Jiao, D., M. Barfield, and V. J. Hruby. 1993. Ab Initio IGLO Study of the ip- and < i-Angle Dependence of the I3C Chemical Shifts in the Model Peptide N-Acetyl-N -methyl-glycinamide. J. Am. Chem. Soc. 115, 10883-10887. 

Stabilization of the systems due to homoconjugation is discussed. 13C and nB NMR chemical shifts of the compounds were also calculated using the individual gauge for localized orbitals (IGLO) method <2000JOC5956>. 

Thus, DFT-IGLO calculations of the 31P chemical shift without spin-orbital corrections yielded a value of S = 274, whereas additional spin-... 

The IGLO method, an important breakthrough for the calculation of magnetic properties, was developed in the mid-1980s by Kutzelnigg et al.2 After some... 

The 13C chemical shift for the central carbon of the protio-tert-butyl dication (8) has been calculated as 327.5 ppm (IGLO/II//MP2/6-31G(d)).30... 

A comparison of IGLO/DZ//MP2/6-31G(d) calculated and measured 13C NMR chemical shifts demonstrates that the partially methyl bridged isomer is the preferred species.36 It was demonstrated that the calculated 13C chemical shifts are highly sensitive toward hyperconjugational distortion, i.e. the degree of bridging (ca. 6ppm/deg from 68° to 98°). 

An experimental and calculational NMR investigation of dicyclopropyl substituted cyclobutylmethyl cation (19)45 has shown that IGLO/DZ//B3LYP/6-31G(d) calculated 13C NMR chemical shifts facilitate the assignment of the spectra. 

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