Desynchronization of pedal motion: Crystallographic and theoretical study of (E)-4-[(4-ethylphenyl)diazenyl]-2-methylphenol

Ocak İskeleli N., KARABIYIK H., Albayrak C., Ağar E.

JOURNAL OF CHEMICAL CRYSTALLOGRAPHY, cilt.38, sa.9, ss.671-677, 2008 (SCI-Expanded) identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 38 Sayı: 9
  • Basım Tarihi: 2008
  • Doi Numarası: 10.1007/s10870-008-9371-5
  • Dergi Adı: JOURNAL OF CHEMICAL CRYSTALLOGRAPHY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.671-677
  • Anahtar Kelimeler: pedal motion, crystal structure, whole-molecule disorder, azobenzene, DFT/B3LYP, RAY CRYSTAL-STRUCTURE, TRANS-STILBENE, BASIS-SET, REFINEMENT
  • Ondokuz Mayıs Üniversitesi Adresli: Evet

Özet

The single crystal X-ray diffraction analysis of the title compound, C15H16N2O, reveals that its molecules exhibit whole-molecule disorder at both crystal lattice sites due to pedal motion in solid state. The compound crystallizes in the monoclinic space group P 2(1)/c with a = 20.5504(14) angstrom, b = 10.8887(5) angstrom, c = 12.0191(8) angstrom and beta = 96.927(5)degrees. While major pedal conformers of the compound in solid state are stabilized by intermolecular O-H center dot center dot center dot N type hydrogen bonds leading to the formation of C(7) chains at Site 1 and C(8) chains at Site 2 along [0 1 0] axis, C-H center dot center dot center dot pi type intermolecular interactions between major and minor conformers also serve to stabilize minor pedal conformers. An interesting feature about the crystal structure is that pedal conformers at Site 1 have two different occupancy factors arising from desynchronization of pedal motion along [2 1 0] direction in crystal phase. Quantum chemical calculations at the B3LYP/6-31++G** level suggest that the desynchronization of pedal motions make more unstable pedal conformers at Site 1 than those at Site 2.