The Basicity of Silylamines and Alkylamines: An Equilibrium Study of the Competitive Borane Adduct Formation

1998 ◽  
Vol 53 (10) ◽  
pp. 1103-1108 ◽  
Author(s):  
Gerald Huber ◽  
Hubert Schmidbaur
Keyword(s):  
Nmr Spectroscopy ◽  
Lewis Acid ◽  
Quantum Chemical ◽  
Adduct Formation ◽  
Steric Effects ◽  
Organic Amine ◽  
Acid Base ◽  
Equilibrium Study ◽  
H Nmr ◽  
Equilibrium Reactions

AbstractIn order to investigate the Lewis acid/base chemistry of silylamines in solution, the equilibrium reactions of Me3SiNMe2 / Me3SiNMe2(BH3) and different amines NR3 / amineboranes NR3(BH3) were monitored by 1H NMR spectroscopy in C6D6 and CDCI3 at 60 °C. For the equilibrium of the reference silylamine/-borane and Me3CNMe2 / Me3CNMe2(BH3) values K = 0.35 (AG = 3.1 kJ mol-1) in C6D6 and K = 0.50 (AG = 2.0 kJ mol-1) in CDCl3 have been estimated, showing that both the silylamine and the C/Si-analogous organic amine have very similar donor properties. Small amines like NMe3 proved to be much more powerful donors than the silylamine Me3SiNMe2, whereas bulky amines are less efficient donors, indicating that steric effects play an important role. The formation of BH3 adducts of Me2NSiH3 and (H3Si)3N which could not be followed experimentally owing to the low stability of the products, has been studied by quantum chemical calculations. A comparison with data for Me3N(BH3) shows that the silylamines are poorer donors, but the reason for this remains unclear

First-principles investigation of the Lewis acid–base adduct formation at the methylammonium lead iodide surface

2018 ◽  
Vol 20 (16) ◽  
pp. 11183-11195 ◽  
Author(s):  
Giacomo Giorgi ◽  
Koichi Yamashita ◽  
Hiroshi Segawa
Keyword(s):  
Lewis Acid ◽  
First Principles ◽  
Adduct Formation ◽  
Lead Iodide ◽  
Acid Base ◽  
Methylammonium Lead Iodide ◽  
Base Formation

Theoretical insights into the mechanism of Lewis acid–base formation at the surface of methylammonium lead iodide (MAPbI3).

An Intramolecular Boron Nitrogen Lewis Acid Base Pair on a Rigid Naphthyl Backbone

2012 ◽  
Vol 67 (6) ◽  
pp. 589-593 ◽  
Author(s):  
Daniel Winkelhaus ◽  
Beate Neumann ◽  
Norbert W. Mitzel
Keyword(s):  
Nmr Spectroscopy ◽  
Single Crystal ◽  
Lewis Acid ◽  
Elemental Analysis ◽  
Base Pair ◽  
Ring System ◽  
X Ray Diffraction ◽  
Acid Base ◽  
X Ray ◽  
Boron Nitrogen

The reaction of (C6F5)2BCl with 8-lithio-N,N-dimethyl-1-naphthylamine (1) afforded the fivemembered ring system 8-bis(pentafluorophenyl)boryl-N,N-dimethyl-1-naphthylamine (2) with an intramolecular dative B-N bond. The compound was characterised by elemental analysis, NMR spectroscopy and single-crystal X-ray diffraction.

Crystallization and grain growth regulation through Lewis acid-base adduct formation in hot cast perovskite-based solar cells

2019 ◽  
Vol 74 ◽  
pp. 172-178 ◽  
Author(s):  
Mohammad Adil Afroz ◽  
Ritesh Kant Gupta ◽  
Rabindranath Garai ◽  
Maimur Hossain ◽  
Suyash Pati Tripathi ◽  
...  
Keyword(s):  
Solar Cells ◽  
Grain Growth ◽  
Lewis Acid ◽  
Growth Regulation ◽  
Adduct Formation ◽  
Acid Base

scholarly journals A pyridinium/anilinium [2]catenane that operates as an acid–base driven optical switch

2018 ◽  
Vol 14 ◽  
pp. 1908-1916 ◽  
Author(s):  
Sarah J Vella ◽  
Stephen J Loeb
Keyword(s):  
Nmr Spectroscopy ◽  
Crown Ether ◽  
Optical Switch ◽  
Protonation State ◽  
Acid Base ◽  
H Nmr ◽  
Recognition Sites ◽  
Yellow Orange ◽  
Deep Yellow ◽  
Orange Color

A two-station [2]catenane containing a large macrocycle with two different recognition sites, one bis(pyridinium)ethane and one benzylanilinium, as well as a smaller DB24C8 ring was synthesized and characterized. 1H NMR spectroscopy showed that the DB24C8 ring can shuttle between the two recognition sites depending on the protonation state of the larger macrocycle. When the aniline group is neutral, the DB24C8 ring resides solely at the bis(pyridinium)ethane site, while addition of acid forms a charged benzylanilinium site. The DB24C8 then shuttles between the two charged recognition sites with occupancy favoring the bis(pyridinium)ethane site by a ratio of 4:1. The unprotonated [2]catenane has a deep yellow/orange color when the DB24C8 ring resides solely at the bis(pyridinium)ethane site and changes to colorless when the crown ether is shuttling (i.e., circumrotating) back and forth between the two recognition sites thus optically signalling the onset of the shuttling dynamics.

The Methylene-bridged Dialuminium Compound R2Al-CH2-AlR2 [R=CH(SiMe3)2] as an Effective Chelating Lewis Acid – Adducts with Halides, Perchlorate and Isopropylamide

2012 ◽  
Vol 67 (10) ◽  
pp. 1081-1090 ◽  
Author(s):  
Werner Uhl ◽  
Christian Rösener ◽  
Christina Stefaniak ◽  
Tim Choy ◽  
Beate Jasper-Peter ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Organic Solvents ◽  
Lewis Acid ◽  
Stoichiometric Ratio ◽  
Acid Base ◽  
X Ray ◽  
X Ray Crystallography ◽  
Coordination Behaviour ◽  
Lewis Acid Adducts ◽  
Oxygen Atoms

The new methylene-bridged dialuminium compound Aryl2Al-CH2-AlAryl2 1b was synthesised from Cl2Al-CH2-AlCl2 and four equivalents of LiAryl [Aryl=C6H2(2,4,6-i-Pr)3]. A 1 : 2 stoichiometric ratio of the starting compounds afforded the dimeric aluminium halide (Aryl2AlCl)2 (2) by dismutation. The coordination behaviour of the related, but more easily available dialuminium compound R2Al-CH2-AlR2 [R=CH(SiMe3)2] 1a was explored. It yields the Lewis acid base adducts [M][R2Al-CH2-AlR2(μ-X)] [3a, M=Li(TMEN)2, X=Cl; 3b, M=Li(TMEN)2, X=Br; 3c, M=K(18-crown-6), X=ClO4; 3d, M=Li(TMEN)2, X=NH(i-Pr)] with X residing in a bridging position between the two Al atoms as evident from NMR spectroscopy and X-ray crystallography (3b, 3c, 3d). Compound 3c is a unique example of a stable, in organic solvents soluble adduct that features a ClO4- anion coordinated by an alkylaluminium compound via two of its oxygen atoms.

Conformational study of blocked pentofuranoses and their 1,5-anhydro derivatives by 1H NMR spectroscopy

1984 ◽  
Vol 49 (1) ◽  
pp. 235-243
Author(s):  
Jaroslav Zajíček ◽  
Miloš Buděšínský ◽  
Jiří Farkaš
Keyword(s):  
Spectral Analysis ◽  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
1H Nmr ◽  
Quantum Chemical ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Conformational Study ◽  
H Nmr

Preferred conformations of the furanose ring and conformer population about the C(5)-C(4) bond in a series of benzoylated pentofuranosyl cyanides have been determined from their 1H NMR spectra. For the 1,5-anhydropentofuranose derivatives the results of the 1H NMR spectral analysis have been compared with the quantum chemical calculations.

5-Chlorouracil and 5-bromouracil acid-base equilibrium study in water and DMSO by NMR spectroscopy

2018 ◽  
Vol 1158 ◽  
pp. 51-56 ◽  
Author(s):  
G.S. Abdrakhimova ◽  
M.Yu Ovchinnikov ◽  
A.N. Lobov ◽  
L.V. Spirikhin ◽  
S.L. Khursan ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Acid Base ◽  
Equilibrium Study ◽  
Base Equilibrium ◽  
Acid Base Equilibrium

Perhalogenated 2-pyridylporphyrin complexes: synthesis, self-coordinating aggregation properties, and catalytic studies

2002 ◽  
Vol 06 (01) ◽  
pp. 50-57 ◽  
Author(s):  
Júlio S. Rebouças ◽  
Maria Eliza M. D. de Carvalho ◽  
Ynara M. Idemori
Keyword(s):  
Nmr Spectroscopy ◽  
First Generation ◽  
Reduction Potential ◽  
Catalyst Concentration ◽  
Acid Base ◽  
H Nmr ◽  
Highly Active ◽  
Ph Dependent ◽  
Metal Insertion ◽  
Kinetics Of

The synthesis of 2, 3, 7, 8, 12, 13, 17, 18-octabromo-meso-tetrakis(2-pyridyl)porphyrin, H 2 Br 8 T 2 PyP , is described, including the comparison of four attempted methods for the demetallation of ZnBr 8 T 2 PyP . One of the methods represents a strategy of demetallation based on the acid-base properties of the macrocycle, the solvent-dependent kinetics of metal insertion into porphyrins and the pH -dependent solubility of the 2-pyridylporphyrin derivatives in water. Self-coordinating aggregation of ZnBr 8 T 2 PyP in non-coordinating solvents was verified by 1 H NMR spectroscopy. The Mn(III)/Mn(II) redox potential for MnBr 8 T 2 PyPCl is 0.38 V higher than the reduction potential measured for its first-generation analogue, MnT 2 PyPCl . Cyclohexane hydroxylation by iodosylbenzene was performed in CH3 CN catalyzed by MnBr 8 T 2 PyPCl and MnT 2 PyPCl . MnBr 8 T 2 PyPCl was highly active, even at low concentration (5 × 10−5 M ), but perhalogenation did not account for oxidative robustness. At such a low catalyst concentration, MnT 2 PyPCl exhibited no activity as inferred by comparison to blank experiments.

scholarly journals Lewis acid complexes of 1,2-diketones and their derivatives. The synthesis of seven-membered rings

1983 ◽  
Vol 61 (9) ◽  
pp. 1981-1986 ◽  
Author(s):  
Christopher Blackburn ◽  
Ronald F. Childs ◽  
Roger A. Kennedy
Keyword(s):  
Nmr Spectroscopy ◽  
Complex Formation ◽  
Lewis Acid ◽  
Proton Resonance ◽  
Vinyl Proton ◽  
Enol Ether ◽  
Charge Delocalization ◽  
Silyl Ethers ◽  
Downfield Shift ◽  
H Nmr

The structures and charge distributions of Lewis and complexes of butane-2,3-dione, 1, cyclohexane-1,2-dione, 2, and 2-methoxycyclohex-2-en-1-one, 5, have been investigated by 1H nmr spectroscopy. A 1:1 complex was formed between 1 and SnCl4 which appeared to have a bridged structure. In the case of 2 and 5 both oxygens were again involved in complex formation with TiCl4 or SnCl4. In each case the large downfield shift of the vinyl proton resonance, H3, indicated extensive charge delocalization within the complexes and that these systems can be regarded as complexed α,β-unsaturated enones. The reactions of Lewis acid complexes of 2, 5, and the silyl ethers 2-(trimethylsiloxy)cyclohex-2-en-1-one, and 3-(trimethylsiloxy)-but-3-en-2-one, 11, with butadiene have been investigated. The acyclic enol ether 11 reacted with butadiene in the presence of either TiCl4 or SnCl4 to give products corresponding to both 4C + 3C and 4C + 2C cycloaddition reactions; in all other cases 4C + 2C products only could be isolated.

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