TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - Spatial magnetic properties subject to lone pair and pi electron delocalization in benzenoid and quinoid structures are quinoid tautomers really nonaromatic?
JF  - Arkivoc : free online journal of organic chemistry
N2  - The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of benzenoid and quinoid tautomeric structures such as benzodifurantrione and phenazine-type molecules have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept of Paul von Rague Schleyer and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values were employed to quantify and visualize the partial aromaticity of the studied compounds. In the case of the surprisingly more stable quinoid tautomers, the aromaticity-synonymous with stability due to the conjugation of p electrons and lone pairs-was not found to be particularly reduced.
KW  - Through-space NMR shieldings (TSNMRS)
KW  - GIAO
KW  - NICS
KW  - benzenoid structures
KW  - quinoid structures
KW  - aromaticity
Y1  - 2012
SN  - 1551-7004
SP  - 94
EP  - 108
PB  - ARKAT
CY  - Gainesville
ER  - 
TY  - JOUR
A1  - Baranac-Stojanovic, Marija
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
T1  - Density Functional Calculations of the Anisotropic Effects of Borazine and 1,3,2,4-Diazadiboretidine
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
N2  - On the basis of the nucleus-independent chemical shift (NICS) concept, the anisotropic effects of two inorganic rings, namely, borazine and planar 1,3,2,4-diazadiboretidine, are quantitatively calculated and visualized as isochemical shielding surfaces (ICSSs). Dissection of magnetic shielding values along the three Cartesian axes into contributions from s and p bonds by the natural chemical shieldingnatural bond orbital (NCSNBO) method revealed that their appearance is not a simple reflection of the extent of (anti)aromaticity.
KW  - anisotropic effects
KW  - aromaticity
KW  - B,N heterocycles
KW  - density functional calculations
KW  - NMR spectroscopy
Y1  - 2012
U6  - https://doi.org/10.1002/cphc.201200732
SN  - 1439-4235
VL  - 13
IS  - 17
SP  - 3803
EP  - 3811
PB  - Wiley-VCH
CY  - Weinheim
ER  -