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1.
Dalton Trans ; 52(4): 947-954, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36597695

RESUMO

The reactions between SnCl2 and three equivalents of the alkali metal phosphido-borane complexes [R2P(BH3)]M yield the corresponding tris(phosphido-borane)stannate complexes [LnM{R2P(BH3)}3Sn] [R2 = iPr2, LnM = (THF)3Li (2Li), (Et2O)Na (2Na), (Et2O)K (2K); R2 = Ph2, LnM = (THF)Li (3Li), (THF)(Et2O)Na (3Na), (THF)(Et2O)K (3K); R2 = iPrPh, LnM = (THF)4Li (4Li)]. In each case X-ray crystallography reveals an anion consisting of a trigonal pyramidal tin centre coordinated by the P atoms of the phosphido-borane ligands. These tris(phosphido-borane)stannate anions coordinate to the alkali metal cations via their BH3 hydrogen atoms in a variety of modes to give monomers, dimers, and polymers, depending on the alkali metal and the substituents at the phosphorus centres. In contrast, reactions between SnCl2 and three equivalents of [tBu2P(BH3)]M (M = Li, Na) gave the known hydride [M{tBu2P(BH3)}2SnH], according to multinuclear NMR spectroscopy.


Assuntos
Boranos , Complexos de Coordenação , Metais Alcalinos , Boranos/química , Compostos de Estanho , Complexos de Coordenação/química , Ânions , Metais Alcalinos/química , Lítio
2.
Magn Reson Chem ; 61(1): 49-54, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36082753

RESUMO

We report a detailed 1 H NMR and 11 B NMR study of as synthesised Li ( BH 3 NH 2 BH 2 NH 2 BH 3 ) obtained in a novel dry-synthesis method. A combination of 1D and 2D single- and triple-quantum techniques was used for the assignment of all observed signals. Minor side-products and reactants were detected in the product: NH 3 BH 3 , Li ( NH 2 BH 3 ) , Li ( BH 4 ) , and two yet unknown salts containing 7-membered chain anions: ( BH 3 NH 2 BH 2 NH 2 BH 2 NH 2 BH 3 ) - and ( BH ( NH 2 BH 3 ) 3 ) - . We believe the assignment provided within this study might be helpful when analysing the mixtures containing numerous ammonia borane derivatives, which often give overlapping signals that are hard to distinguish.


Assuntos
Boranos , Amônia/química , Ânions , Boranos/química , Espectroscopia de Ressonância Magnética , Lítio/química , Prótons
3.
Molecules ; 27(23)2022 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-36500299

RESUMO

The decomposition of ammonia borane (NH3BH3) to produce hydrogen has developed a promising technology to alleviate the energy crisis. In this paper, metal and non-metal diatom-doped CoP as catalyst was applied to study hydrogen evolution from NH3BH3 by density functional theory (DFT) calculations. Herein, five catalysts were investigated in detail: pristine CoP, Ni- and N-doped CoP (CoPNi-N), Ga- and N-doped CoP (CoPGa-N), Ni- and S-doped CoP (CoPNi-S), and Zn- and S-doped CoP (CoPZn-S). Firstly, the stable adsorption structure and adsorption energy of NH3BH3 on each catalytic slab were obtained. Additionally, the charge density differences (CDD) between NH3BH3 and the five different catalysts were calculated, which revealed the interaction between the NH3BH3 and the catalytic slab. Then, four different reaction pathways were designed for the five catalysts to discuss the catalytic mechanism of hydrogen evolution. By calculating the activation energies of the control steps of the four reaction pathways, the optimal reaction pathways of each catalyst were found. For the five catalysts, the optimal reaction pathways and activation energies are different from each other. Compared with undoped CoP, it can be seen that CoPGa-N, CoPNi-S, and CoPZn-S can better contribute hydrogen evolution from NH3BH3. Finally, the band structures and density of states of the five catalysts were obtained, which manifests that CoPGa-N, CoPNi-S, and CoPZn-S have high-achieving catalytic activity and further verifies our conclusions. These results can provide theoretical references for the future study of highly active CoP catalytic materials.


Assuntos
Boranos , Diatomáceas , Amônia , Metais , Hidrogênio , Modelos Teóricos
4.
BMC Plant Biol ; 22(1): 585, 2022 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-36517759

RESUMO

BACKGROUND: Cold stress adversely influences rapeseeds (Brassica napus L.) growth and yield during winter and spring seasons. Hydrogen (H2) is a potential gasotransmitter that is used to enhance tolerance against abiotic stress, including cold stress. However, convenience and stability are two crucial limiting factors upon the application of H2 in field agriculture. To explore the application of H2 in field, here we evaluated the role of ammonia borane (AB), a new candidate for a H2 donor produced by industrial chemical production, in plant cold tolerance. RESULTS: The application with AB could obviously alleviate the inhibition of rapeseed seedling growth and reduce the oxidative damage caused by cold stress. The above physiological process was closely related to the increased antioxidant enzyme system and reestablished redox homeostasis. Importantly, cold stress-triggered endogenous H2S biosynthesis was further stimulated by AB addition. The removal or inhibition of H2S synthesis significantly abolished plant tolerance against cold stress elicited by AB. Further field experiments demonstrated that the phenotypic and physiological performances of rapeseed plants after challenged with cold stress in the winter and early spring seasons were significantly improved by administration with AB. Particularly, the most studied cold-stress response pathway, the ICE1-CBF-COR transcriptional cascade, was significantly up-regulated either. CONCLUSION: Overall, this study clearly observed the evidence that AB-increased tolerance against cold stress could be suitable for using in field agriculture by stimulation of H2S signaling.


Assuntos
Boranos , Brassica napus , Brassica rapa , Sulfeto de Hidrogênio , Brassica napus/metabolismo , Sulfeto de Hidrogênio/metabolismo , Amônia , Resposta ao Choque Frio , Brassica rapa/metabolismo , Plantas/metabolismo
5.
Molecules ; 27(23)2022 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-36500373

RESUMO

An efficient, high-yielding and scalable procedure for the regioselective 3-acylation of indoles with anhydrides promoted by boron trifluoride etherate under mild conditions was reported. This novel protocol provided a simple way to prepare 3-(benzofuran-2-yl) indole in three steps.


Assuntos
Anidridos , Boranos , Estrutura Molecular , Acilação
6.
Molecules ; 27(19)2022 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-36234729

RESUMO

2,4,6-Trichloro-1,3,5-triazine (cyanuric chloride) is an excellent coupling reagent for the preparation of highly structured multifunctional molecules. Three component systems based on porphyrin, cyanuric chloride and carborane clusters were prepared by a one-pot stepwise amination of cyanuric chloride with 5-(4-aminophenyl)-10,15,20-triphenylporphyrin, followed by replacement of the remaining chlorine atoms with carborane S- or N-nucleophiles. Some variants of 1,3,5-triazine derivatives containing porphyrin, carborane and residues of biologically active compounds such as maleimide, glycine methyl ester as well as thioglycolic acid, mercaptoethanol and hexafluoroisopropanol were also prepared. A careful control of the reaction temperature during the substitution reactions will allow the synthesis of desired compounds in a good to high yields. The structures of synthesized compounds were determined with UV-vis, IR, 1H NMR, 11B NMR, MALDI-TOF or LC-MS spectroscopic data. The dark and photocytotoxicity as well as intracellular localization and photoinduced cell death for compounds 8, 9, 17, 18 and 24 were evaluated.


Assuntos
Boranos , Porfirinas , Cloro , Espectroscopia de Ressonância Magnética , Maleimidas , Mercaptoetanol , Estrutura Molecular , Porfirinas/química , Triazinas/química
7.
Chemosphere ; 309(Pt 1): 136674, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36195122

RESUMO

Although the reducing property of morpholine borane is frequently used, there are few studies on its use as a chemical hydrogen storage material. This study presents the catalyst efficiency for hydrogen production in the dehydrogenation reaction of morpholine borane as efficient and cost-effective hydrogen storage material, which can be used as an alternative to depleting fossil fuels. It was studied with four different catalysts as activated Carbon-supported Pd, PdAg, PdNi, and PdCo. Bimetallic palladium based catalysts were used for the dehydrogenation of morpholine borane for the first time. Nanoparticles were synthesized using the chemical reduction method. The catalytic effects of different metal ratios of PdNi/C nanoparticles, which were concluded to have the best catalyst effect, were investigated and it was observed that the ratio of Pd50Ni50/C nanoparticles exhibited better catalytic behavior, and optimization studies were carried out with Pd50Ni50/C nanoparticles. Transmission Electron Microscopy, X-Ray Diffraction, and X-Ray Photoelectron Spectroscopy analyzes were performed for the characterization of nanoparticles. According to the characterization analyzes of Pd50Ni50/C nanoparticles, the mean particle size was determined as 2.0 ± 1.0 nm. Catalyst efficiency was determined by performing the substrate, catalyst, and temperature experiments separately in the dehydrogenation reaction of Morpholine Borane. These parameters are respectively; Ea and ΔH were calculated as 93.2 kJ/mol, and 90.6 kJ/mol. The reusability experiments were carried out in 4 cycles. In other words, with this study, it was concluded that the reusability of Pd50Ni50/C nanoparticles synthesized by the chemical method is high and their catalytic activity is excellent.


Assuntos
Boranos , Boranos/química , Paládio/química , Carvão Vegetal , Hidrogênio/química , Morfolinas , Combustíveis Fósseis
8.
Environ Sci Process Impacts ; 24(11): 2085-2099, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36165287

RESUMO

Fluorochemicals are a persistent environmental contaminant that require specialized techniques for degradation and capture. In particular, recent attention on per- and poly-fluoroalkyl substances (PFAS) has led to numerous explorations of different techniques for degrading the super-strong C-F bonds found in these fluorochemicals. In this study, we investigated the hydrodefluorination mechanism using silylium-carborane salts for the degradation of PFAS at the density functional theory (DFT) level. We find that the degradation process involves both a cationic silylium (Et3Si+) and a hydridic silylium (Et3SiH) to facilitate the defluorination and hydride-addition events. Additionally, the role of carborane ([HCB11H5F6]-) is to force unoccupied anti-bonding orbitals to be partially occupied, weakening the C-F bond. We also show that changing the substituents on carborane from fluorine to other halogens weakens the C-F bond even further, with iodic carborane ([HCB11H5I6]-) having the greatest weakening effect. Moreover, our calculations reveal why the C-F bonds are resistant to degradation, and how the silylium-carborane chemistry is able to chemically transform these bonds into C-H bonds. We believe that our results are further applicable to other halocarbons, and can be used to treat either our existing stocks of these chemicals or to treat concentrated solutions following filtration and capture.


Assuntos
Boranos , Fluorcarbonetos , Hexaclorobenzeno , Catálise , Flúor
9.
J Org Chem ; 87(18): 12065-12071, 2022 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-36053236

RESUMO

The condensative cyclization of sp3 C-O bonds in per-silylated hexitols is investigated by computation. Conformer searches using the Monte Carlo algorithm, followed by successively higher levels of theory (MMFF, PM3, and B3LYP), of -SiR3+- and -Bcat+-activated substrates lead to structures primed for intramolecular chemistry. Silane activation features O4 to C1 attack, while borane activation suggests boronium ions that activate O5 to C2 reactivity. This, in conjunction with Boltzmann population analysis, parallels reported reactivity for sorbitol, mannitol, and galactitol. Calculations using the meta-hybrid M06-2X functional additionally provide free-energy profiles for each cyclization event. In most of the cases presented, precyclization conformers that position a nucleophilic oxygen less than 3.0 Å from the C-O leaving group correlate to efficient experimental reactivities. Two examples of galactitol containing bridging silyl groups are analyzed computationally, and the experimental outcomes match predictions. The computational regime presented is a step closer to providing predictive power for the reduction of per-functionalized molecules.


Assuntos
Boranos , Silanos , Ciclização , Galactitol , Íons , Manitol , Oxigênio/química , Sorbitol , Álcoois Açúcares
10.
Org Lett ; 24(40): 7440-7445, 2022 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-36173131

RESUMO

The metal-free reductive N-trifluoroethylation and N-trifluoroacetylation of indoles have been developed. Bench stable and inexpensive trimethylamine borane and trifluoroacetic acid (TFA) were utilized as the reductive and fluorinating reagents, respectively. These transformations were switchable on the basis of altering the loading of trimethylamine borane and TFA. Preliminary experiments indicated indoline was the common intermediate in these two transformations.


Assuntos
Boranos , Indóis , Metilaminas , Ácido Trifluoracético
11.
Inorg Chem ; 61(36): 14282-14287, 2022 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-36047676

RESUMO

Herein, we report the synthesis of a benzimidazolylidene-stabilized borane adduct and its borenium ion. This borenium ion was used as a metal-free catalyst for hydrogenating various substituted quinoline N-heterocycles under ambient conditions. Furthermore, this method was utilized to synthesize two drug molecules: galipinine and angustureine. A detailed DFT study was performed to understand this metal-free catalytic hydrogenation.


Assuntos
Boranos , Catálise , Hidrogenação
12.
Dalton Trans ; 51(34): 12895-12903, 2022 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-35942906

RESUMO

The high fluorophilicity of borane-containing ligands offers promise for accessing new metallodrug candidates capable of bifunctional [18F]-positron emission tomography (PET) imaging, but this requires water soluble and hydrolytically stable ligands that can be fluorinated under mild conditions. Toward this goal, here we report the synthesis and characterization of water-soluble Pt(II) complexes containing a triaminoborane-bridged diphosphoramidite ligand called MeOTBDPhos that can be fluorinated using simple fluoride salts. NMR and XRD studies show that (MeOTBDPhos)PtCl2 (1) dissolves in water with cooperative H-OH addition across the bridgehead N-B bond to form 1-H2O. The B-OH bond in 1-H2O undergoes rapid displacement with fluoride (<10 min) when treated with CsF in MeCN to form 1-HF. 1-HF can also be prepared in <10 min by addition of KF to 1 in the presence Kryptofix® 222 and (HNEt3)Cl in MeCN. In addition to using fluoride salts, we show how mononuclear 1 can be fluorinated with HBF4·Et2O to form dinuclear [(MeOTBDPhos-HF)Pt(µ-Cl)]2(BF4)2 (4-HF). Comparative studies show that the B-F bond in 1-HF undergoes hydrolysis as soon as it is dissolved in water or saline, but the B-F bond persists for hours when the pH of the solution is lowered to pH ≤ 2. In contrast to 1-HF, the B-F bond in dinuclear 4-HF persists for days when dissolved in water, which may be attributed to slow, sacrificial release of fluoride from the BF4- anion. The results show how cooperative N-B reactivity on the ligand can be leveraged to rapidly fluorinate water-soluble MeOTBDPhos complexes under mild conditions and afford suggestions for how to enhance hydrolytic B-F stability, as required for use in biomedical applications.


Assuntos
Boranos , Platina , Fluoretos , Halogenação , Hidrólise , Ligantes , Sais , Água
13.
Int J Mol Sci ; 23(15)2022 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-35955965

RESUMO

New anti-octadecaborane(22) laser dyes have been recently introduced. However, their application in solid thin films is limited, despite being very desirable for electronics. Spectroscopic methods, photoluminescence (PL), and infrared reflection-absorption spectroscopy (IRRAS), are here used to reveal structural responses to a temperature change in thin polymer films made of π- and σ-conjugated and non-conjugated polymers and anti-octadecaborane(22) and its tetra-alkylatedderivatives. It has been observed that borane clusters are not firmly fixed within polymer matrices and that their ability for diffusion out of the polymer film is unprecedented, especially at higher temperatures. This ability is related to thermodynamic transitions of polymer macromolecular chains. PL and IRRAS spectra have revealed a clear correlation with ß-transition and α-transition of polymers. The influence of structure and molecular weight of a polymer and the concentration and the substitution type of clusters on mobility of borane clusters within the polymer matrix is demonstrated. A solution is proposed that led to an improvement of the temperature stability of films by 45 °C. The well-known spectroscopic methods have proved to be powerful tools for a non-routine description of the temperature behavior of both borane clusters and polymer matrices.


Assuntos
Boranos , Polímeros , Corantes , Lasers , Polímeros/química , Espectrofotometria Infravermelho , Temperatura
14.
Chem Commun (Camb) ; 58(71): 9910-9913, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35979664

RESUMO

Structural characterization of the complex [B(ß-pinane)3] (1) reveals non-covalent H⋯H contacts that are consistent with the generation of London dispersion energies involving the ß-pinane ligand frameworks. The homolytic fragmentations of 1, and camphane and sabinane analogues ([B(camphane)3] (2) and [B(sabinane)3] (3)) were studied computationally. Isodesmic exchange results showed that London dispersion interactions are highly dependent on the terpene's stereochemistry, with the ß-pinane framework providing the greatest dispersion free energy (ΔG = -7.9 kcal mol-1) with Grimme's dispersion correction (D3BJ) employed. PMe3 was used to coordinate to [B(ß-pinane)3], giving the complex [Me3P-B(ß-pinane)3] (4), which displayed a dynamic coordination equilibrium in solution. The association process was found to be slightly endergonic at 302 K (ΔG = +0.29 kcal mol-1).


Assuntos
Boranos , Monoterpenos Bicíclicos , Canfanos , Ligantes , Terpenos
15.
J Am Chem Soc ; 144(34): 15793-15802, 2022 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-35973127

RESUMO

Two borane-functionalized bidentate phosphine ligands that vary in tether length have been prepared to examine cooperative metal-substrate interactions. Ni(0) complexes react with aryl azides at low temperatures to form structurally unusual κ2-(N,N)-N3Ar adducts. Warming these adducts affords products of N2 extrusion and in one case, a Ni-imido compound that is capped by the appended borane. Reactions with 1-azidoadamantane (AdN3) provide a distinct outcome, where a proposed nickel imido intermediate activates the sp2 C-H bonds of arenes, even in the presence of benzylic C-H sites. Combined experimental and computational mechanistic studies demonstrate that the unique reactivity is a consequence of Lewis-acid-induced polarization of the Ni-NR bond, potentially providing a synthetic strategy for chemoselective reaction engineering.


Assuntos
Boranos , Ácidos de Lewis , Azidas/química , Ligantes , Níquel/química
16.
Angew Chem Int Ed Engl ; 61(43): e202209655, 2022 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-35973965

RESUMO

Terminal iron nitrides (Fe≡N) have been proposed as intermediates of Fe-mediated nitrogen fixation, and well-defined synthetic iron nitrides have been characterized in high oxidation states, including FeIV , FeV , and FeVI . This study reports the generation and low temperature characterization of a terminally bound iron(III) nitride, P3 B Fe(N) (P3 B =tris(o-diisopropylphosphinophenyl)borane), which is a proposed intermediate of iron-mediated nitrogen fixation by the P3 B Fe-catalyst system. CW- and pulse EPR spectroscopy (HYSCORE and ENDOR), supported by DFT calculations, help to define a 2 A ground state electronic structure of this C3 -symmetric nitride species, placing the unpaired spin in a sigma orbital along the B-Fe-N vector; this electronic structure is distinct for an iron nitride. The unusual d5 -configuration is stabilized by significant delocalization (≈50 %) of the unpaired electron onto the axial boron and nitrogen ligands, with a majority of the spin residing on boron.


Assuntos
Boranos , Ferro , Ferro/química , Ligantes , Fixação de Nitrogênio , Boro , Espectroscopia de Ressonância de Spin Eletrônica , Nitrogênio/química
17.
J Org Chem ; 87(16): 10928-10936, 2022 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-35921205

RESUMO

The Cu(OTf)2/NBS-mediated tandem reaction of 1-cinnamyl alcohol-o-carboranes for the synthesis of C-alkenyl-o-carboranes has been developed. Mechanism studies demonstrated that the Cu(OTf)2-promoted ring opening of oxetane with electron-rich arenes as soft nucleophiles was involved and was the key step for the transformation. This work provided an alternative strategy for the synthesis of C-alkenyl-o-carboranes, which has an important reference for the synthesis of o-carborane derivatives with diversity.


Assuntos
Boranos , Éteres Cíclicos , Propanóis
18.
Int J Mol Sci ; 23(16)2022 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-36012608

RESUMO

Amines play an important role in synthesizing drugs, pesticides, dyes, etc. Herein, we report on an efficient catalyst for the general construction of amine mediated by nickel boride nanoclusters supported by a TS-1 molecular sieve. Efficient production of amines was achieved via catalytic hydrogenation of N=X (X = C, O, H) bonds. In addition, the catalyst maintains excellent performance upon recycling. Compared with the previous reports, the high activity, simple preparation and reusability of the Ni-B catalyst in this work make it promising for industrial application in the production of amines.


Assuntos
Aminas , Boranos , Aminação , Aminas/química , Catálise , Níquel/química
19.
Dalton Trans ; 51(30): 11558-11566, 2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-35848404

RESUMO

Six iron(0) tricarbonyl complexes (1a-f) with a η4-1-azadiene moiety were prepared and their performance in the hydroboration of unsaturated organic compounds was investigated. All the complexes exhibit catalytic activity towards hydroboration of ketones, aldehydes and aldimines with pinacolborane (HBpin) as a hydride source to lead to secondary alcohols, primary alcohols, and secondary amines, respectively, after hydrolysis of the hydroboration products. Of the iron(0) tricarbonyl complexes, complex 1e is the most robust one and was employed throughout the catalytic investigation. Its preference towards the three types of substrates is as follows: aldimines > aldehydes ≫ ketones. In total, 24 substrates were examined for the catalytic hydroboration reactivity and generally, isolation yields ranging from 40% to 95% were achieved. Mechanistic investigation suggests that the catalytic hydroboration of the substrates proceeds via intramolecular hydride transfer without going through an Fe-H intermediate. As indicated by 1H NMR spectroscopic monitoring, the substrates and the borane agent bind to the iron centre and the imine N atom, respectively, which facilitates the hydride transfer by activating the B-H bond and polarizing the double bond of the substrates.


Assuntos
Aldeídos , Boranos , Álcoois/química , Aldeídos/química , Boranos/química , Catálise , Cetonas/química
20.
Molecules ; 27(14)2022 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-35889339

RESUMO

Based on the acid-base neutralization, the (1-methylimidazolium)(tetrazol-1-yl)borane was successfully synthesized by taking advantage of the acidity of the tetrazole and the basicity of the 1-methylimidazole borane complex. Through HRMS, NMR, and FT-IR, the structure of synthetic compounds was characterized in detail. Concerning about the (1-methylimidazolium)(tetrazol-1-yl)borane, it had an ignition-delay time of about 25 ms and a density specific impulse over 351 s·g/cm3, making it a suitable candidate for green hypergolic fuels. Moreover, it also demonstrated that introducing tetrazole into the borane could be an appropriate strategy to adjust the performance of the energy of those borane compounds.


Assuntos
Boranos , Imidazóis , Espectroscopia de Infravermelho com Transformada de Fourier , Tetrazóis/química
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