N-p-Tolylvanillaldimine, C15H15NO2

Kaitner, Branko; Pavlović, Gordána

doi:10.1107/s0108270195002824

Cited by 8 publications

(7 citation statements)

References 7 publications

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“…[12] Although general trends should be assessed with caution, the presence of one hydroxy group at positions other than the ortho-aryl carbon atom, relative to the aldehyde group, usually moves the Schiff base to a phenol-imine structure. [13][14][15][16] Clearly, an intramolecular hydrogen bond between the iminic nitrogen atom and the OH group at the ortho position is required to facilitate tautomer interconversion by hydrogen transfer.…”

Section: Introductionmentioning

confidence: 99%

Schiff Bases from TRIS and ortho‐Hydroxyarenecarbaldehydes: Structures and Tautomeric Equilibria in the Solid State and in Solution

Martínez¹,

Авалос²,

Babiano³

et al. 2011

Eur J Org Chem

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Three Schiff bases generated by conventional condensation of a simple aminopolyol (TRIS) and 5‐bromo‐ and 5‐iodosalicylaldehyde, and 2‐hydroxy‐1‐naphthaldehyde, have been fully characterized, both in solution and in the solid state. This study provides a complete analysis of imine–enamine equilibria, and sheds light onto the mechanism of hydrogen transfer, which has been controversial in the literature. Low‐temperature X‐ray diffraction accompanied by electron‐density maps have further been complemented by theoretical studies at the B3LYP/6‐31G* and M06‐2X/6‐311++G** levels. To ascertain the influence of crystal packing on tautomeric stability, the lattice has also been simulated by computation. This protocol involves the assessment of a supramolecular cluster around a core tautomer possessing either imine or enamine structures. Such an analysis, in full agreement with solid‐state data, reveals the greater stability of zwitterionic structures for the salicyl derivatives. In contrast, these substances show preferential imine forms in solution, whereas the naphthyl‐based compound exhibits a prevalent keto‐enamine structure in all cases.

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Section: Introductionmentioning

confidence: 99%

Schiff Bases from TRIS and ortho‐Hydroxyarenecarbaldehydes: Structures and Tautomeric Equilibria in the Solid State and in Solution

Martínez¹,

Авалос²,

Babiano³

et al. 2011

Eur J Org Chem

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“…In connection with our research aimed at developing various metallo-organic compounds [18][19][20][21][22][23], we investigated the tautomeric equilibrium in the solid state and solution of the uncoordinated ligands, that is, Schiff-bases [24,25].…”

Section: Introductionmentioning

confidence: 99%

Nitroaniline Derivatives of 2-Oxo-1-naphthylideneamines—Molecular Self-Assembling via C—H⋯O Intermolecular Hydrogen Bonds and Stabilization of O—H⋯N and N—H⋯O Tautomers in Solution and Solid State

et al. 2004

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Three Schiff-bases of the Ar CH N Ar type were synthesized from 2-hydroxy-1-naphthaldehyde and o-(1), m-(2), and p-nitroaniline (3) in order to investigate the shift of the keto-amine/enol-imine tautomeric equilibrium that arises by the introduction of the electron-withdrawal nitro group. The compounds have been investigated experimentally, in the solid state and in the solution, by IR, NMR, UV spectroscopy, and X-ray single crystal analysis, and theoretically by using density functional theory (DFT). The tautomeric equilibrium is strongly shifted towards the keto-amine form despite of the nitro group position at N -phenyl ring in the solid state of molecular structures of 1, 2, and 3 (especially indicated by C O and C N bond distances). The keto-amine tautomeric form of the compounds is characterized by a strong, resonance assisted hydrogen bond (RAHB) of the N H · · · O type (the N· · ·O distances are 2.530(8), 2.554(2) and 2.555(5)Å in 1, 2, and 3, respectively). The molecules are assembled in the crystalline state into a 3D HB network (1), centrosymmetrical dimers (2) or infinite chains (3) by the C H · · · O intermolecular hydrogen bonds. In contrast, UV/VIS spectra of the chloroform solution of the title compounds reveal predominance of the enol-imine form. The molecular geometries and relative stabilities of the compounds determined by using DFT find good agreement with the experimental data.

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“…Instead, a free hydrogen bond donor (hydroxyl group) and an acceptor (imino group) are available for intermolecular hydrogen bonding. This can be observed in the structure of N-(4-methylphenyl)-hydroxy-3-methoxybenzilideneamine[111] where intermolecular O-H•••N hydrogen bonds of 2.84 Å connect the molecules into chains(Figure 13).Increasing the size of the N-substituent renders the participation of hydrogen donors and acceptors of the central keto-amino group in intermolecular bonding less probable. In such cases, and if additional hydrogen donors and acceptors are absent, the packing is governed by weak interactions.…”

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confidence: 98%

Schiff bases derived from hydroxyaryl aldehydes: molecular and crystal structure, tautomerism, quinoid effect, coordination compounds

Blagus

Cinčić

Friščić

et al. 2010

Maced. J. Chem. Chem. Eng.

105

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During the last 50 years a vast number of structural studies on Schiff bases derived from hydroxyaryl aldehydes and their coordination compounds have been undertaken. In this review we present a systematic and brief overview of the most important discoveries and achievements accomplished in this field. The occurrence of Schiff bases (and their complexes) derived from nine most commonly used hydroxyaryl aldehydes in the Cambridge Structural Database (CSD) has been investigated. Keto-enol tautomerism and intramolecular hydrogen bonding in salicylaldimines and naphthaldimines is discussed, with a comment of the most common errors in determining the correct tautomeric form. Also, the interrelationship of crystal packing and the substituents on the Schiff base is studied. Finally, we give a short overview of conformational differences between free Schiff bases and Schiff bases bonded to metal ions as well as some structural characteristics of Schiff base metal complexes.

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N-p-Tolylvanillaldimine, C15H15NO2

Cited by 8 publications

References 7 publications

Schiff Bases from TRIS and ortho‐Hydroxyarenecarbaldehydes: Structures and Tautomeric Equilibria in the Solid State and in Solution

Schiff Bases from TRIS and ortho‐Hydroxyarenecarbaldehydes: Structures and Tautomeric Equilibria in the Solid State and in Solution

Nitroaniline Derivatives of 2-Oxo-1-naphthylideneamines—Molecular Self-Assembling via C—H⋯O Intermolecular Hydrogen Bonds and Stabilization of O—H⋯N and N—H⋯O Tautomers in Solution and Solid State

Schiff bases derived from hydroxyaryl aldehydes: molecular and crystal structure, tautomerism, quinoid effect, coordination compounds

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