A theoretical and experimental NMR study of the tautomerism of two phenylene-bis-C-substituted pyrazoles

Sanz, Dionísia; Claramunt, Rosa M.; Alkorta, Ibón; Elguero, José; Thiel, Werner R.; Rüffer, Tobias

doi:10.1039/b803855d

Cited by 18 publications

(8 citation statements)

References 35 publications

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“…Both pyrazole rings act as proton‐donating (N1) and ‐accepting (N2) sites for intermolecular hydrogen bonds. This results in the formation of a complex three‐dimensional network structure, wherein pyrazole tetramers3,9d,10 are involved as the linking centres (Figure 1, centre). The network contains three‐dimensional pores, filled by the butyl chains.…”

Section: Resultsmentioning

confidence: 99%

Ruthenium Complexes Bearing N–H Acidic Pyrazole Ligands

et al. 2010

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Chelate ligands containing at least one pyrazole group were treated with RuCl2(PPh3)3, RuHCl(CO)(PPh3)3 and RuH2(CO)(PPh3)3 to form ruthenium complexes bearing protic N–H groups in close proximity to the catalytically active ruthenium centre. In the case of the hydridoruthenium complex RuHCl(CO)(PPh3)3 the resulting complexes also contain abasic hydrido ligand. The combination of acidic and basic hydrogen species in one molecule and the arising two‐site reactivity was thoroughly investigated spectroscopically and by DFT calculations. Catalytic tests on the hydrogenation and transfer hydrogenation of acetophenone showed a general activity of these systems.

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Section: Resultsmentioning

confidence: 99%

Ruthenium Complexes Bearing N–H Acidic Pyrazole Ligands

et al. 2010

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“…Further more, pyrazoles dimerization in the gas phase also has been reported [21][22][23]. On the other hand, the tautomerism and proton transfer in pyrazoles have been communicated [24][25][26][27]. Recently, we studied the solid state structures and anti-microbial activity of some new substituted pyrazoles [28,29].…”

Section: Introductionmentioning

confidence: 92%

Cooperative N–H···N, N–H···O, and O–H···N bonded molecular dimers of two new 3,5-diaryl-1H-pyrazoles

Zheng

Wang

2010

Struct Chem

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Two new 3,5-diaryl-1H-pyrazoles: 3(5)-(4-tertbutylphenyl)-5(3)-(naphthalene-2-yl)-1H-pyrazole (1) and 5-(4-(benzyloxy)phenyl)-3-(furan-2-yl)-1H-pyrazole (2) were synthesized and characterized. Two strong ions peaks [2M] ? and [2M ? Na] ? observed in the ESI-MS spectra are attributed to the dimerization process in solution formed by intermolecular N-HÁÁÁN hydrogen bonds. The crystal structures have been determined by X-ray crystal structure analysis. Compound 1 exists as a pair of tautomers 1a and 1b, and its dimer [R 2 2 (6) motif] is formed by the tautomers 1a and 1b. Compound 2 only exists as a 2a tautomer, and interesting intermolecular N-HÁÁÁO and O-HÁÁÁN hydrogen bonds link two pyrazoles and two methanol molecules, leading to the formation of an R 4 4 (10) dimer motif.

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“…We have devoted several papers to the aromaticity of azoles (related to those of Scheme 2.4) and to the effect of their protonation (azolium salts) [88][89][90][91]. We published a paper discussing phosphole (46, M ¼ PH), pyrrole (36), and their tetrahydro derivatives where NICS were used to assess their aromaticity.…”

Section: Nics and Aromaticitymentioning

confidence: 99%

“…The next publication deals with a compound of the 52 class, the fully nitrogenated N 8 molecule, pentazolo[1,2-a]pentazole (56) [94]. According to the NICS calculated values, this molecule is more aromatic than benzene and pyrrole (36). The aromaticity of 56 increases by complexation with anions ( Figure 2.3).…”

Section: Nics and Aromaticitymentioning

confidence: 99%

“…a) Continuum models: shielding constants (chemical shifts). Only in a few papers [14,35,36], we carried out GIAO/B3LYP/6-311 þþ G(d,p) calculations on bromopyrazoles in DMSO using the PCM model. On the other hand, many authors have used continuum models to calculate shielding constants [173][174][175][176], especially important are those of Ruud and coworkers [177,178].…”

Section: Solvent Effectsmentioning

confidence: 99%

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