Low temperature crystal and molecular structure of nitrobenzene

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.     

Interactions of polar hydrogen bond donor solvents with ions: a theoretical study

Structural Chemistry - Intermolecular interactions between molecules of protic solvents (water, methanol, formic acid, formamide, methylamine and ammonia) and monatomic ions (Li+, Na+, K+,...     

Comparison of the substituent effects in tetrazole systems and benzene. A computational study

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 2p_z orbitals at all atoms of the tetrazole and benzene derivatives were correlated with the sum of occupation overall 2p_z 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 2p_z orbital and pEDA were found for all atoms except N4.     

How π-electron delocalisation reflects replacement of H+ with Li+ in variously substituted malonaldehydes

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.