Substituent steric effects and molecular structure of anionic σ-complexes of 5,7-dinitroquinoline

Influence of Cation on Molecular and Electronic Structures of Meisenheimer Complexes. Theoretical Topological Analysis of Electron Density Function

“…Anionic σ-complexes or Meisenheimer complexes (MC) are very important class of compounds that are a key intermediate in nucleophilic aromatic substitution reactions forming the backbone of numerous important syntheses of pharmaceuticals and potential drugs and several other classes of bioactive agents 1 . Our previous investigations 2,3 of an electron density distributions in MC have shown noticeable potassium cation impact on this distribution. Now we report an explicit study of an influence of cations on molecular and electronic structures of MC.…”

N-{2-[(3,5-Di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)amino]phenyl}-N-(5,7-dinitroquinolin-8-yl)-1-phenylmethanesulfonamide: the nature of intramolecular shortened contacts

“…The steric strain in this fragment of (I) is con®rmed by a number of shortened intramolecular contacts, which are listed in Table 1. Nevertheless, nearly symmetrical steric interactions between the atoms of a dihydrocycle and several substituents could result in planarity of the ring (Borbulevych et al, 2000). Apparently, a similar situation occurs in (I), since the positions of the tert-butyl groups are symmetrical relative to the C23Á Á ÁC26 direction.…”

X-ray Diffraction and Ab Initio Quantum-Chemical Study of the Charge Density in the Crystals of Meisenheimer ComplexesDerivatives of 2,4,6-Trinitrobenzene and 5,7-Dinitroquinoline

“…Preliminary X-ray structural data for compounds 1 and 2 were reported in the recent past. , Single crystals of 1 and 2 were obtained by a slow evaporation of the water and acetonitrile solutions, respectively. Crystallographic data and results of the multipole refinements are summarized in Table .…”

“…Probably, structural investigations of spirocyclic anionic σ-complexes are more promising in this respect because these MCs were found to form relatively good and stable single crystals. Our recent studies of MCs were devoted to the conformational analysis of similar spirocyclic compounds, , or the study of zwitterionic Meisenheimer complexes. − Moreover, we have investigated, for the first time, the charge density distribution in the crystal of the Meisenheimer complex of the potassium 3-methyl-5‘,7‘-dinitro-5‘,8‘-dihydrospiro(1,3-oxazolidine-2,8‘-quinolinide) . This preliminary study has demonstrated that the electronic structure of the anionic σ-complex is drastically influenced by the manner of potassium cation coordination to the organic anion.…”