- The X-ray crystal and molecular structure of 3,5-di-tert-butylpyrazole hydrochloride at 200 K
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The title compound 1H,2H-3,5-di-tert-butylpyrazolium chloride (2) was prepared by reacting 1H-3,5-di-tert-butylpyrazole (1) with hydrochloric acid in methanol.The molecules of 2 are arrenged in the crystal in dimers bridged by the chlorine ion through strong and quite linear hydrogen bonds.Several surveys were performed via the Cambridge Structural Datebase searching for N+(sp2)-H...Cl- interactions and for prseudo-rings in which two chlorine ions were hydrogen bonded by two water molecules, both hydrogen atoms of each molecule being involved in the contacts.
- Fernandez-Castano, Cristina,Foces-Foces, Concepcion,Jagerovic, Nadine,Elguero, Jose
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- Direct Evidence for Neutral N-Pyrazolyl Radicals: Paddlewheel Dibismuthanes Bearing Pyrazolato Ligands with Very Short Bi-Bi Single Bonds
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Neutral N-pyrazolyl radicals [3,5-R2pz]? as reactive intermediates were generated by one-electron oxidization of the corresponding 3,5-disubstituted pyrazolato anions [3,5-R2pz]- (R = tBu, Ph) with BiCl3 and trapped by the use of 5,5-dimethyl-1-pyrroline-N-oxide as a spin trap, which was confirmed by electron paramagnetic resonance spectral analysis. With dimerization of the postulated pyrazolato low-valent BiII radical species, two novel paddlewheel pyrazolatodibismuthanes [L2(Bi-Bi)L2] [L = η1,η1-3,5-R2pz; R = tBu (5α, 5β, and 5γ), Ph (6)] were isolated and structurally characterized.
- Zhao, Ming-Gang,Hao, Ting-Ting,Zhang, Xiang,Ma, Jian-Ping,Su, Ji-Hu,Zheng, Wenjun
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- Li+, Cu+, and Ag+ oligonuclear structures with the sterically demanding bis(3,5-tertbutylpyrazol-1-yl)dithioacetate heteroscorpionate ligand
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The heteroscorpionate N2S2 donor ligand bis(3,5-tertbutylpyrazol-1-yl)dithioacetate (L) was prepared as a Li+ trinuclear complex, which co-crystallizes with tetrahydrofuran (THF) solvent molecules: [Li(L)]3(2.25)THF. When [Li(L)]3 was reacted with AgBF4 or [Cu(CH3CN)4]BF 4, the oligonuclear species [Ag(L)]3 and [Cu 5(L)4]BF4 were isolated and structurally characterized. The Ag+ complex presents an irregular trinuclear structure in which three AgL moieties define a central trigonal site that may potentially host a fourth metal ion. The Cu+ complex exhibits a highly symmetric pentanuclear structure in which four equivalent CuL moieties shape an internal tetrahedral site occupied by an additional Cu+ ion. According to electrospray-mass spectrometry (ESI-MS) and 1H diffusion NMR spectroscopy, the Ag+ and Cu+ complexes maintain oligonuclear structures in solution. In particular, the Cu+ pentanuclear complex, once dissolved, rapidly equilibrates with the tetranuclear species [Cu4(L)3]+. This is confirmed by the presence of two sets of NMR signals, which demonstrated a change in ratio at different complex concentrations effected by a NMR dilution titration. Variable temperature NMR experiments (210-303 K) defined the activation parameters associated with the fluxional behavior of [Cu5(L)4]BF 4 and [Cu4(L)3]+, and these results are consistent with intramolecular rearrangements in both species (ΔS ? 0).
- Bassanetti, Irene,Gennari, Marcello,Marchio, Luciano,Terenghi, Mattia,Elviri, Lisa
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- Synthesis, crystal structure and photophysical study of luminescent three-coordinate cuprous bromide complexes based on pyrazole derivatives
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The 1: 2 M-ratio reaction between cuprous bromide and pyrazole derivatives in toluene results in mononuclear Cu(I) complexes [CuBr(pyrazole)2]. The complexes have been characterized by 1H NMR spectroscopy and elemental analysis. The molecular structure, established by single-crystal X-ray diffraction, features a trigonal planar geometry around copper, with monodentate pyrazole derivatives. All the Cu(I) complexes are luminescent in the solid state at ambient temperature. Intense blue or blue-green emission in the solid state is observed for these complexes, with the maxima ranging from 431 to 493 nm. The observed photoluminescence could be ascribed to the metal-to-ligand charge-transfer excited states, probably mixed with some halide-to-ligand character. The microsecond lifetime scale of the complexes implies that these transitions arise from the triplet excited states.
- Wu, Fengshou,Tong, Hongbo,Wang, Kai,Zhang, Xiulan,Zhang, Jie,Wong, Wai-Kwok,Zhu, Xunjin
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- Versatile Tri(pyrazolyl)phosphanes as Phosphorus Precursors for the Synthesis of Highly Emitting InP/ZnS Quantum Dots
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Tri(pyrazolyl)phosphanes (5R1,R2) are utilized as an alternative, cheap and low-toxic phosphorus source for the convenient synthesis of InP/ZnS quantum dots (QDs). From these precursors, remarkably long-term stable stock solutions (>6 months) of P(OLA)3 (OLAH=oleylamine) are generated from which the respective pyrazoles are conveniently recovered. P(OLA)3 acts simultaneously as phosphorus source and reducing agent in the synthesis of highly emitting InP/ZnS core/shell QDs. These QDs are characterized by a spectral range between 530–620 nm and photoluminescence quantum yields (PL QYs) between 51–62 %. A proof-of-concept white light-emitting diode (LED) applying the InP/ZnS QDs as a color-conversion layer was built to demonstrate their applicability and processibility.
- Panzer, René,Guhrenz, Chris,Haubold, Danny,Hübner, René,Gaponik, Nikolai,Eychmüller, Alexander,Weigand, Jan J.
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supporting information
p. 14737 - 14742
(2017/10/23)
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- Solvent-free synthesis of 3,5-di-tert-butylpyrazole and 3,5-di-substitutedbutylpyrazol-1-ylethanol
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A high-yield, solvent-free approach to the synthesis of 1,3,5-trisubstituted pyrazoles is reported. Four compounds, (3,5-di-tert-butyl- 1H-pyrazole, (2-(3,5-dimethyl-1H-pyrazol-1-yl)ethanol, 2-(3,5-di-tert-butyl-1H- pyrazol-1-yl)ethanol, 2-(3,5-diphenyl-1
- Van Wyk, Juanita L.,Omondi, Bernard,Appavoo, Divambal,Guzei, Ilia A.,Darkwa, James
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p. 474 - 477
(2012/10/29)
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- 5-Hydroxy-2-pyrazolines and some of their 1-substituted analogs
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The use of 1,3-dicarbonyl compounds containing strong electron-withdrawing substituents (perfluoroalkyl, 4-nitrophenyl) at one of the carbonyl groups in reaction with hydrazine or its monosubstituted derivatives (4-nitro- and 2,4-dinitrophenylhydrazines) leads to the formation of stable intermediates for the synthesis of pyrazoles (5-hydroxy-2-pyrazolines) or their linear tautomers (hydrazones).
- Zelenin,Tugusheva,Yakimovich,Alekseev,Zerova
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p. 668 - 676
(2007/10/03)
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- 5-Hydroxy-4,5-Dihydropyrazoles
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The use of β-diketones with strong electron-withdrawing substituents in reaction with hydrazine and its monosubstituted derivatives leads to the stable intermediates of pyrazole synthesis - 5-hydroxy-4,5-dihydropyrazoles or their open chain isomers.
- Zelenin, Kirill N.,Alekseyev, Valery V.,Tygysheva, Alja R.,Yakimovitch, Stanislav I.
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p. 11251 - 11256
(2007/10/02)
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