Structural and aromatic aspects for tautomerism of (Z)-6-((4-bromophenylamino)methylene)-2,3-dihydroxycyclohexa-2,4-dienone
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Tarih
2009
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Springer/Plenum Publishers
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
The molecular and crystal structure of (Z)-6-((4-bromophenylamino)methylene)-2,3-dihydroxycyclohexa- 2,4-dienone were determined by single crystal X-ray diffraction and spectroscopic methods. Molecules of the compound can be regarded as a resonance hybrid of cis-keto tautomer and zwitterionic form. Pairs of molecules of the compound generate pseudocyclic centrosymmetric R-2(2)(10) supramolecular synthons with the aid of O-H center dot center dot center dot O type intermolecular H-bonds. Stacking of R-2(2)(10) synthons along b-axis is stabilized by pi center dot center dot center dot pi interactions. Changes in both covalent topology and molecular geometry of the compound accompanying proton transfer were monitored by a relaxed PES scan with respect to hydroxyl bond length used as redundant internal coordinate. Quantum chemical studies at 6-311 + G(d,p) level reveal that bond lengths which are indicative to tautomerization process cannot reach their expected values even if proton transfer occurs in gas phase and pseudo-aromatic chelate ring formation has primary effect on the stabilization of NH tautomer. Resonance-assisted intramolecular H-bond affects the electronic state of its neighboring aromatic fragments.
Açıklama
Anahtar Kelimeler
Schiff base, Tautomerism, Resonance-assisted H-bond (RAHB), pi-electron coupling, HOMA
Kaynak
Structural Chemistry
WoS Q Değeri
Q2
Scopus Q Değeri
Q2
Cilt
20
Sayı
6
