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Roland Boese Dieter Bläser Michael Nussbaumer Tadeusz Marek Krygowski 《Structural chemistry》1992,3(5):363-368
The crystal and molecular structure of nitrobenzene was determined at 103 K by X-ray diffraction, yieldingR=0.034 and a highly precise geometry of the molecule (esds of bond lengths 0.001 Å and bond angles 0.1°). The bond angles in the ring agree very well with additive scheme based on angular substituent parameters. X-X electron density maps support the view that the C-N bond does not exhibit-character, and, hence, the nitro group interacts with the ring mostly by inductive effects. 相似文献
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Bodwell GJ Bridson JN Cyrañski MK Kennedy JW Krygowski TM Mannion MR Miller DO 《The Journal of organic chemistry》2003,68(6):2089-2098
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Natural Population Analysis of two tautomeric forms of 16 tetrazole derivatives substituted at carbon atom (AlH2, BeH, BH2, CCH, CF3, CHO, Cl, CN, F, Me, NH2, NO, NO2, OH, SH, SiH3) was carried out at B3LYP/6-31G(d,p) level of theory and compared with data for monosubstituted benzene derivatives. The individual occupancies of 2pz orbitals at all atoms of the tetrazole and benzene derivatives were correlated with the sum of occupation overall 2pz orbitals, named pEDA(A) or pEDA(B), respectively. These characteristics correlate well with the Hammett-like substituent constants. Acceptable correlations between the individual atom occupancies at the 2pz orbital and pEDA were found for all atoms except N4. 相似文献
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Correlations were studied between the properties of Bader's ring and bond critical points calculated for variously substituted
malonaldehyde (containing intramolecular H-bond) and its π-electron delocalisation expressed by aromaticity indices HOMA and NICSs. It was observed that π-electron delocalisation of the system strongly depends on the substituent and its position. Replacement of the H+ with Li+ in malonaldehyde allowed us to study the role of unoccupied 2p orbital in π-electron delocalisation. In the case of lithium system the aromaticity is increased as compared with the malonaldehyde itself
and moreover with the malonaldehyde anion. This proves that the unoccupied 2p orbital of Li+ may play a significant role in delocalisation of π-electrons due to its low orbital energy. In the case of lithium system the substituent effect is negligible, which resembles
the situation in benzene derivatives.
Dedicated to Prof. Karl Jug on the occasion of his 65th birthday anniversary. 相似文献
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Tadeusz M. Krygowski Piotr K. Wrona Urszula Zielkowska Christian Reichardt 《Tetrahedron》1985,41(20):4519-4527
Empirical parameters of Lewis acidity, ENT, introduced by Reichardt et al., and Lewis basicity, BKT , introduced by Kamlet and Taft, have been determined for mixtures of water with ten organic solvents. In the case of water/alcohol mixtures a distinct dependence between these acidity and basicity parameters have been found. For the other solvent mixtures the ENT on BKT dependence is more complex even if these parameters are purified from non-specific solute/solvent interactions. 相似文献
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