PM3 semiempirical study and its comparison with X-ray crystal structure of 2-methyl-4-(4-methoxyphenylazo)phenol

Abstract

The crystal and molecular structure of 2-methyl-4-(4-methoxyphenylazo)phenol have been determined by X-ray single crystal diffraction technique. The compound crystallizes in the monoclinic space group P2 1 /c with a = 9.7763(8) Å, b = 11.3966(8) Å, c = 11.9531(8) Å and β = 108.752(6) • . In addition to the molecular geometry from X-ray experiment, its optimized molecular structure has been obtained with the aid of PM3 semiempirical quantum mechanical method, and then the corresponding geometric parameters were compared with those of X-ray crystallography. To determine conformational flexibility and crystal packing effects on the molecules, molecular energy profile of the title compound was obtained with respect to two selected degrees of torsional freedom, which were varied from −180 • to +180 • in steps of 10 • . Crystal structure of the title compound is a fibroid structure constructed by C-H···O and O-H···N type intermolecular hydrogen bonds. The most favorable conformer of the title compound has been determined by the crystal packing effects and there is no

Crystallographic and conformational analysis of two novel trans-azo benzene compounds

“…Some selected geometrical parameters experimentally obtained and their calculated values are listed in Table 2. The N=N bond distances in both compounds (Table 2) are in agreement with the corresponding values of similar compounds [24][25][26][27][28][29] and reflect their double bond character. The bond lengths of pairs of formally single C-N bonds at opposite sides around azo bridges are not sensitive to substituent effects and thus, they are almost equal in both compounds ( Table 2) single C-N bonds at opposite sides around azo bridges in both compounds are slightly different from each other due to a possible through-resonance effect between the electron-donating O atom and the two-electron accepting N atom.…”

Crystallographic and conformational analysis of (E)-2-isopropyl-4-(p-tolyldiazenyl)phenol

“…Some selected geometrical parameters experimentally obtained and theoretically calculated are listed in Table 2. The N=N bond distances are in agreement with the corresponding values of similar compounds [22][23][24]. In Residue 2, nitrogen atoms have the site occupancy factor of 0.539(6) in major and 0.461(6) in minor component.…”

“…In Residue 2, nitrogen atoms have the site occupancy factor of 0.539(6) in major and 0.461(6) in minor component. While pairs of formally single C-N bonds at opposite sides around azo bridges in Residue 1 are comparable in their bond lengths, in Residue 2 they are slightly different from each other due to a possible through-resonance effect between the electron-donating O atom and the two-electron accepting N atom as is in similar compounds [22][23][24][25][26][27].…”

Conformational analysis and crystal structure of (E)-3-methyl-4-(p-tolyldiazenyl)phenol

“…In the title compound, the aromatic rings, which adopt a distorted trans configuration around the N=N double bond, are not coplanar with the value of − 166.69(10) • for the pedal angle. In the azo groups, C7-N2 and C4-N1 bond lengths, which re- [20][21][22][23][24][25][26][27][28]. N2-C7 and N1-C4 bond distance are of remarkable difference due to a possible through-resonance effect between the electron-donating hydroxyl group and the two-electronaccepting N atom.…”