scholarly journals Understanding How Lewis Acids Dope Organic Semiconductors: A “Complex” Story

2021 ◽  
Author(s):  
Pablo Simon Marques ◽  
Giacomo Londi ◽  
Brett Yurash ◽  
Thuc-Quyen Nguyen ◽  
Stephen Barlow ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Lewis Acids ◽  
Computational Studies

We report on computational studies of the potential of three borane Lewis acids (LAs) (B(C6F5)3 (BCF), BF3, and BBr3) to form stable adducts and/or to generate positive polarons with three...

Tropylium Salt Promoted Hydroboration Reactions: Mechanistic Insights via Experimental and Computational Studies

2021 ◽  
Author(s):  
Nhan Nu Hong Ton ◽  
Binh Khanh Mai ◽  
Thanh Vinh Nguyen
Keyword(s):  
Dft Calculations ◽  
Lewis Acids ◽  
Experimental Studies ◽  
Cross Coupling ◽  
Computational Studies ◽  
Metal Free ◽  
Hydride Abstraction ◽  
Novel Method ◽  
Tropylium Salts

Abstract: Hydroboration reaction of alkynes is one of the most synthetically powerful tools to access organoboron compounds, versatile precursors for cross coupling chemistry. This type of reaction has traditionally been mediated by transition metal or main group catalysts. Herein, we report a novel method using tropylium salts, typically known as organic oxidants and Lewis acids, to efficiently promote the hydroboration reaction of alkynes. A broad range of vinylboranes can be easily accessed via this metal-free protocol. Similar hydroboration reactions of alkenes and epoxides can also be efficiently catalyzed by the same tropylium catalysts. Experimental studies and DFT calculations suggested that the reaction follows an uncommon mechanistic paradigm, which is triggered by a hydride abstraction of pinacolborane with tropylium ion. This is followed by a series of <i>in situ</i> counterion-activated substituent exchanges to generate boron intermediates that promote the hydroboration reaction.

scholarly journals Towards understanding the doping mechanism of organic semiconductors by Lewis acids

2019 ◽  
Vol 18 (12) ◽  
pp. 1327-1334 ◽  
Author(s):  
Brett Yurash ◽  
David Xi Cao ◽  
Viktor V. Brus ◽  
Dirk Leifert ◽  
Ming Wang ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Lewis Acids ◽  
Doping Mechanism

scholarly journals Coordination Behavior of [Cp″2Zr(µ1:1-As4)] towards Lewis Acids

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2966
Author(s):  
Veronika Heinl ◽  
Gábor Balázs ◽  
Sarah Koschabek ◽  
Maria Eckhardt ◽  
Martin Piesch ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Lewis Acid ◽  
Reaction Temperature ◽  
Lewis Acids ◽  
Computational Studies ◽  
Coordination Modes ◽  
Coordination Numbers ◽  
Coordination Behavior

The functionalization of the arsenic transfer reagent [Cp″2Zr(η1:1-As4)] (1) focuses on modifying its properties and enabling a broader scope of reactivity. The coordination behavior of 1 towards different Lewis-acidic transition metal complexes and main group compounds is investigated by experimental and computational studies. Depending on the steric requirements of the Lewis acids and the reaction temperature, a variety of new complexes with different coordination modes and coordination numbers could be synthesized. Depending on the Lewis acid (LA) used, a mono-substitution in [Cp″2Zr(µ,η1:1:1:1-As4)(LA)] (LA = Fe(CO)4 (4); B(C6F5)3 (7)) and [Cp″2Zr(µ,η3:1:1-As4)(Fe(CO)3)] (5) or a di-substitution [Cp″2Zr(µ3,η1:1:1:1-As4)(LA)2] (LA = W(CO)5 (2); CpMn(CO)2 (3); AlR3 (6, R = Me, Et, iBu)) are monitored. In contrast to other coordination products, 5 shows an η3 coordination in which the butterfly As4 ligand is rearranged to a cyclo-As4 ligand. The reported complexes are rationalized in terms of inverse coordination.

Lewis Acid Coordination Redirects S-Nitrosothiol Reduction

2020 ◽  
Author(s):  
Valiallah Hosseininasab ◽  
Alison C. McQuilken ◽  
Abolghasem (Gus) Bakhoda ◽  
Jeffery A. Bertke ◽  
Qadir K. Timerghazin ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Lewis Acids ◽  
Reduction Potential ◽  
Chemical Reduction ◽  
Physiological Responses ◽  
Outer Sphere ◽  
Intramolecular Electron Transfer ◽  
Computational Studies ◽  
Reduction Potentials ◽  
Initial Reduction

<i>S</i>-Nitrosothiols (RSNOs) serve as air-stable reservoirs for nitric oxide in biology and are responsible for a myriad of physiological responses. While copper enzymes promote NO release from RSNOs by serving as Lewis acids capable of intramolecular electron-transfer, redox innocent Lewis acids separate these two functions to reveal the effect of coordination on structure and reactivity. The synthetic Lewis acid B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordinates to the RSNO oxygen atom in adducts RSNO-B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, leading to profound changes in the RSNO electronic structure and reactivity. Although RSNOs possess relatively negative reduction potentials (-1.0 to -1.1 vs. NHE), B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordination increases their reduction potential by over 1 V into the physiologically accessible +0.1 V vs. NHE. Outer-sphere chemical reduction results in formation of the Lewis acid stabilized hyponitrite dianion <i>trans</i>-[LA–O–N=N–O–LA]<sup>2–</sup> (LA = B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>) that releases N<sub>2</sub>O upon acidification. Mechanistic and computational studies support initial reduction to the [RSNO-B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>]<sup>•/- </sup>radical-anion susceptible to N-N coupling prior to loss of RSSR.

Cyanide and Azide Anion Complexation by a Bidentate Stibonium-Borane Lewis Acid

2014 ◽  
Vol 69 (11-12) ◽  
pp. 1199-1205 ◽  
Author(s):  
Casey R. Wade ◽  
François P. Gabbaï
Keyword(s):  
Lewis Acid ◽  
Lewis Acids ◽  
Natural Bond Orbital ◽  
Orbital Method ◽  
Computational Studies ◽  
Cyanide Complex ◽  
Acid Anion ◽  
Anion Complexation ◽  
Azide Ligand ◽  
Complex Features

Abstract Our ongoing interest in the chemistry of polyfunctional Lewis acids has led us to investigate the reaction of the stibonium-borane [o-(Ph2MeSb)(Mes2B)C6H4]+ (1+) with cyanide and azide, two toxic anions. Both anions react with 1+ to afford the corresponding neutral complexes 1-CN and 1-N3. Structural and computational studies show that the coordinated anion interacts with both the boron and antimony atoms of the bidentate Lewis acid. While the azide complex features a typical κ2N1 : N1 bridging azide ligand, the cyanide complex possesses a cyanoborate moiety whose cyanide interacts side-on with the stibonium center. The Lewis acid-anion interactions observed in these complexes have also been studied computationally using the Natural Bond Orbital method

scholarly journals Protonation-Induced Charge Transfer and Polaron Formation in Organic Semiconductors Doped by Lewis Acids

2022 ◽  
Author(s):  
Fabian Bauch ◽  
Chuanding Dong ◽  
Stefan Schumacher
Keyword(s):  
Electron Transfer ◽  
Organic Semiconductors ◽  
Polymer Chain ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Positive Charge ◽  
Excitation Spectra ◽  
Vertical Excitation ◽  
Detailed Interpretation ◽  
P Type

Lewis acid doping of organic semiconductors (OSCs) opens up new ways of p-type doping and has recently become of significant interest. As for the mechanistic understanding, it was recently proposed that upon protonation of the OSC backbone, electron transfer occurs between the protonated polymer chain and a neutral chain nearby, inducing a positive charge carrier in the latter [Nat. Mater. 18, 1327 (2019)]. To further clarify the underlying microscopic processes on a molecular level, in the present work, we analyze the influence of protons on the electronic properties of the widely used PCPDT–BT copolymer. We find that single protonation of the polymer chain leads to the formation of a polaron coupled to the position of the proton. Upon protonation of the same chain with a second proton, an intrachain electron transfer occurs, leaving behind a polaron largely decoupled from the proton positions. We also observe the possibility of an interchain electron transfer from a neutral chain to a double protonated chain in agreement with the mechanism recently proposed in the literature. The simulated vertical excitation spectra for an ensemble of protonated species with different amounts of protons enable a detailed interpretation of experimental observation on PCPDT–BT doped with the Lewis acid BCF. Our results further suggest that multi-protonation plays an important role for completing the mechanistic picture of Lewis acid doping of OSCs.

Lewis Acid Coordination Redirects S-Nitrosothiol Reduction

2020 ◽  
Author(s):  
Valiallah Hosseininasab ◽  
Alison C. McQuilken ◽  
Abolghasem (Gus) Bakhoda ◽  
Jeffery A. Bertke ◽  
Qadir K. Timerghazin ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Lewis Acids ◽  
Reduction Potential ◽  
Chemical Reduction ◽  
Physiological Responses ◽  
Outer Sphere ◽  
Intramolecular Electron Transfer ◽  
Computational Studies ◽  
Reduction Potentials ◽  
Initial Reduction

<i>S</i>-Nitrosothiols (RSNOs) serve as air-stable reservoirs for nitric oxide in biology and are responsible for a myriad of physiological responses. While copper enzymes promote NO release from RSNOs by serving as Lewis acids capable of intramolecular electron-transfer, redox innocent Lewis acids separate these two functions to reveal the effect of coordination on structure and reactivity. The synthetic Lewis acid B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordinates to the RSNO oxygen atom in adducts RSNO-B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, leading to profound changes in the RSNO electronic structure and reactivity. Although RSNOs possess relatively negative reduction potentials (-1.0 to -1.1 vs. NHE), B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordination increases their reduction potential by over 1 V into the physiologically accessible +0.1 V vs. NHE. Outer-sphere chemical reduction results in formation of the Lewis acid stabilized hyponitrite dianion <i>trans</i>-[LA–O–N=N–O–LA]<sup>2–</sup> (LA = B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>) that releases N<sub>2</sub>O upon acidification. Mechanistic and computational studies support initial reduction to the [RSNO-B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>]<sup>•/- </sup>radical-anion susceptible to N-N coupling prior to loss of RSSR.

scholarly journals Tropylium Salt Promoted Hydroboration Reactions: Mechanistic Insights via Experimental and Computational Studies

2021 ◽  
Author(s):  
Nhan Nu Hong Ton ◽  
Binh Khanh Mai ◽  
Thanh Vinh Nguyen
Keyword(s):  
Dft Calculations ◽  
Lewis Acids ◽  
Experimental Studies ◽  
Cross Coupling ◽  
Computational Studies ◽  
Metal Free ◽  
Hydride Abstraction ◽  
Novel Method ◽  
Tropylium Salts

Abstract: Hydroboration reaction of alkynes is one of the most synthetically powerful tools to access organoboron compounds, versatile precursors for cross coupling chemistry. This type of reaction has traditionally been mediated by transition metal or main group catalysts. Herein, we report a novel method using tropylium salts, typically known as organic oxidants and Lewis acids, to efficiently promote the hydroboration reaction of alkynes. A broad range of vinylboranes can be easily accessed via this metal-free protocol. Similar hydroboration reactions of alkenes and epoxides can also be efficiently catalyzed by the same tropylium catalysts. Experimental studies and DFT calculations suggested that the reaction follows an uncommon mechanistic paradigm, which is triggered by a hydride abstraction of pinacolborane with tropylium ion. This is followed by a series of <i>in situ</i> counterion-activated substituent exchanges to generate boron intermediates that promote the hydroboration reaction.

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