Tautomerism in Schiff bases derived from 3-hydroxysalicylaldehyde. Combined X-ray diffraction, solution and solid state NMR study

Pizzala, Hélène; Carles, Micheline; Stone, William E.; Thevand, André

doi:10.1039/b000756k

Cited by 65 publications

(57 citation statements)

References 21 publications

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“…[13] The resonances at low field are due to the hydrogen bonds between N and O, which show a coupling with the imine CH group as well as with the CH group of the spacer. Complexes of similarly protonated salicylimines are frequently found, e.g.…”

Section: Coordination Chemistry Of Ligand 3-h 6 With Titanium(iv) Andmentioning

confidence: 98%

Protonation of Tris(iminocatecholato) Complexes of Gallium(III) and Titanium(IV)

et al. 2007

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The coordination behaviour of the chiral tren-type tripodal ligand 3-H 6 with gallium(III) and titanium(IV) ions was investigated and it was found that only mononuclear complexes are formed. In the presence of Na + , one of the cations acts as a template and is bound inside the "cap" of [Na(3)M]n-(M = Ga, n = 2; M = Ti, n = 1). If no such cation is present, three protons are bound to the iminocatechol units in order to prevent repulsion between lone pairs at nitrogen and oxygen. To minimize the charge repulsion between the protonated imines of [H 3 (3)M]n+ (M = Ga, n = 0; M = Ti, n = 1), an enamin-

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Section: Coordination Chemistry Of Ligand 3-h 6 With Titanium(iv) Andmentioning

confidence: 98%

Protonation of Tris(iminocatecholato) Complexes of Gallium(III) and Titanium(IV)

et al. 2007

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“…The C2-O1 bond distance values follow into the range (1.277(2)-1.302(3)Å) found for the structures of the ketoamine naphthylideneamines [44][45][46].…”

Section: Crystal Structure Descriptionmentioning

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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“…[21][22][23] Schiff bases derived from ohydroxyaromatic aldehydes and ketones have shown to be excellent models for the study of keto-enol tautomerism both in solution and in the solid state. [24][25][26][27][28] Such Schiff bases have drawn attention due to their physical properties in the crystalline state which are greatly influenced by the topochemistry of the Schiff base molecules which in turn is highly affected by the crystal structure. [29][30][31][32][33] During the past decade it became wellrecognised that solvent-free synthesis and mechanochemistry are effective for the efficient and rapid synthesis of a wide range of imines.…”

Section: Introductionmentioning

confidence: 99%

Controlling Solvate Formation of a Schiff Base by Combining Mechano-chemistry with Solution Synthesis

et al. 2012

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Abstract. A Schiff base dicarboxylic acid (1) was prepared by condensation of 2-hydroxy-1-naphthaldehyde with 5-aminoisophthalic acid. Its solvates with pyridine (2a and 2b) and dimethylformamide (3) were prepared by liquid-assisted grinding and by conventional solvent-based methods. All products were characterised by FT-IR spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The structures of 1, 2b and 3 were determined by single crystal X-ray diffraction. 1 was found to be a pure Schiff base, 2b a pyridine solvate and 3 a dimethylformamide solvate monohydrate. In all three structures, the Schiff base molecule appears to be present as the ketoamine tautomer.(doi: 10.5562/cca2111)

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Tautomerism in Schiff bases derived from 3-hydroxysalicylaldehyde. Combined X-ray diffraction, solution and solid state NMR study

Cited by 65 publications

References 21 publications

Protonation of Tris(iminocatecholato) Complexes of Gallium(III) and Titanium(IV)

Protonation of Tris(iminocatecholato) Complexes of Gallium(III) and Titanium(IV)

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

Controlling Solvate Formation of a Schiff Base by Combining Mechano-chemistry with Solution Synthesis

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