Synthesis and Aggregation Properties of Two‐ and Three‐Armed Nitrogen‐Rich Chelate Ligands: Novel Bis(<i>N</i>‐acylamidines), Tris(<i>N</i>‐acylamidines) and Bis(triazapentadienes) with Flexible or Rigid Spacers

Clodt, Juliana Isabel; Wigbers, Christof; Reiermann, Ralph; Fröhlich, Roland; Würthwein, Ernst‐Ulrich

doi:10.1002/ejoc.201100218

Cited by 13 publications

(14 citation statements)

References 31 publications

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“…Both structures show E ‐configuration of the C=N bond and a sickle‐type arrangement of the almost planar central O=C–N=C(H)–N(R 2 ) chain with dihedral angles for the O=C–N=C unit of 17.4(2)° ( 5c ) vs. 11.8(2)° ( 5f ) and –168.2(2)° ( 5c ) vs. –171.0(1)° ( 5f ) for the C–N=C–N unit. The bond lengths along the O=C–N=CH–N chain are 1.224(2), 1.365(2), 1.299(2) and 1.313(2) Å for 5c , and 1.233(2), 1.373(2), 1.317(2) and 1.311(2) Å for 5f , indicating the dominating resonance interaction along the conjugated hetero system 9j,9l…”

Section: Resultsmentioning

confidence: 99%

N‐Acyl‐ and N‐Sulfonylformamidines from Cyanamides and Carbodiimides by Hydroalumination and Subsequent Treatment with Electrophiles

et al. 2013

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Hydroalumination of cyanamides 1 with di(isobutyl)aluminium hydride affords intermediate compounds 3, which have dimeric structures in the solid state with four‐membered Al2N2 heterocycles and exocyclic N=C double bonds. The reactions of 3 with acyl chlorides yield N′,N′‐disubstituted N‐acylformamidines 5, whereas reaction with sulfonyl chlorides give the corresponding N‐sulfonylformamidines 7. In contrast, carbodiimides 8 react with dialkylaluminium hydrides R2AlH (R = tBu, iBu) to give compounds 9 in which one C=N bond of the carbodiimide is reduced to form an amidinate ligand and a second molecule of the hydride is coordinated through an Al–N and an Al–H–Al bond. Treatment of 9 with acyl chlorides yields N,N′‐disubstituted N‐acylformamidines 10, whereas reaction with sulfonyl chlorides gives the corresponding N‐sulfonylformamidines 11.

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Section: Resultsmentioning

confidence: 99%

N‐Acyl‐ and N‐Sulfonylformamidines from Cyanamides and Carbodiimides by Hydroalumination and Subsequent Treatment with Electrophiles

et al. 2013

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“…16 Bis-and tris-triazapentadiene ligands 6c-e: the procedure used for 6b is also the basis for the preparation of the bis-triazapentadienes 6c-d 20 and the novel three-armed tristriazapentadiene ligand 6e (Scheme 3).…”

Section: Synthesismentioning

confidence: 99%

“…The bistriazapentadiene ligands 6c and 6d including their precursors (11c-13c, 11d-13d) were synthesized following a literature procedure. 20 Melting points are uncorrected. Nuclear magnetic Fig.…”

Section: General Proceduresmentioning

confidence: 99%

Fluorescent benzene-centered mono-, bis- and tris-triazapentadiene–boron complexes

et al. 2015

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A series of novel benzene centered mono-, bis-and tris-1,3,5-triazapentadiene ligands 6a-e was synthesized and investigated with respect to their reactivity towards triphenylborane. The resulting blue-fluorescent boron complexes 14a-e with a six-membered ring chelate structure show excellent thermal and chemical stability. All title compounds were completely characterized including X-ray diffraction studies for 14a-c and 14e. Whereas the absorption spectra of all three classes of compounds are similar, the fluorescence spectra show distinct differences. Thus, the emission spectra of 14a,b show Stokes shifts of 4100-6700 cm −1 with low quantum yields both in solution and in the solid state. However, the more bulky compounds 14c-e show markedly larger molar extinction coefficients and smaller bathochromic shifts compared to 14a,b. For all compounds, we observe significantly more intense red-shifted fluorescence in the solid state compared to that in dichloromethane solutions. For the interpretation of the absorption properties TD-DFT studies were performed based on DFT geometry optimizations.

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“…[61][62][63][229][230][231][232][233] Compared with b-enaminones or b-enaminoimines, the nitrogen atom at the 3-position alters the electronic structures considerably so that conjugation extends over all five atoms. [61][62][63][229][230][231][232][233] Compared with b-enaminones or b-enaminoimines, the nitrogen atom at the 3-position alters the electronic structures considerably so that conjugation extends over all five atoms.…”

Section: Synthesis Of 135-triazapentadienesmentioning

confidence: 99%

Resonance‐Assisted Hydrogen Bonding as a Driving Force in Synthesis and a Synthon in the Design of Materials

Mahmudov

Pombeiro

2016

Chemistry A European J

145

100

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Resonance-assisted hydrogen bonding (RAHB), a concept introduced by Gilli and co-workers in 1989, concerns a kind of intramolecular H-bonding strengthened by a conjugated π-system, usually in 6-, 8-, or 10-membered rings. This Review highlights the involvement of RAHB as a driving force in the synthesis of organic, coordination, and organometallic compounds, as a handy tool in the activation of covalent bonds, and in starting moieties for synthetic transformations. The unique roles of RAHB in molecular recognition and switches, E/Z isomeric resolution, racemization and epimerization of amino acids and chiral amino alcohols, solvatochromism, liquid-crystalline compounds, and in synthons for crystal engineering and polymer materials are also discussed. The Review can provide practical guidance for synthetic chemists that are interested in exploring and further developing RAHB-assisted synthesis and design of materials.

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Synthesis and Aggregation Properties of Two‐ and Three‐Armed Nitrogen‐Rich Chelate Ligands: Novel Bis(N‐acylamidines), Tris(N‐acylamidines) and Bis(triazapentadienes) with Flexible or Rigid Spacers

Cited by 13 publications

References 31 publications

N‐Acyl‐ and N‐Sulfonylformamidines from Cyanamides and Carbodiimides by Hydroalumination and Subsequent Treatment with Electrophiles

N‐Acyl‐ and N‐Sulfonylformamidines from Cyanamides and Carbodiimides by Hydroalumination and Subsequent Treatment with Electrophiles

Fluorescent benzene-centered mono-, bis- and tris-triazapentadiene–boron complexes

Resonance‐Assisted Hydrogen Bonding as a Driving Force in Synthesis and a Synthon in the Design of Materials

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