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Synthesis, characterization, anion c...

Chiu, Ching-Wen.

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Synthesis, characterization, anion complexation and electrochemistry of cationic Lewis acids.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Synthesis, characterization, anion complexation and electrochemistry of cationic Lewis acids./
Author:	Chiu, Ching-Wen.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2008,
Description:	204 p.
Notes:	Source: Dissertations Abstracts International, Volume: 70-04, Section: B.
Contained By:	Dissertations Abstracts International70-04B.
Subject:	Inorganic chemistry. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3321663
ISBN:	9780549721482

Synthesis, characterization, anion complexation and electrochemistry of cationic Lewis acids.
Chiu, Ching-Wen.

Synthesis, characterization, anion complexation and electrochemistry of cationic Lewis acids. - Ann Arbor : ProQuest Dissertations & Theses, 2008 - 204 p.

Source: Dissertations Abstracts International, Volume: 70-04, Section: B.

Thesis (Ph.D.)--Texas A&M University, 2008.

This item is not available from ProQuest Dissertations & Theses.

Owing to the favored Coulombic attraction between the ammonium group and anion which stabilizes the B-F/B-CN bond against heterolysis, cationic borane [25]+ has great affinity toward anions than its neutral analog, and is capable of capturing fluoride or cyanide from water under bi-phasic conditions. By placing the fluorophilic silyl group adjacent to an electrophilic carbocation, a novel fluoride sensor [ 45]+ was obtained. Sensing occurs via a fluoride induced methyl migration from the silicon to adjacent electrophilic methylium center which is unprecedented. As a result of its strong fluoride affinity, [ 45]+ is able to react with KF in aqueous media at pH 7.0. The electrochemistry study of these cationic Lewis boranes reveals that the cationic character of these boranes serves to decrease their reduction potential and increase the stability of the resulting radicals. In this part of the research, we have prepared a cationic borane [27] +, which features two reversible reduction waves at -0.86 and -1.56 (vs. Fc/Fc+) corresponding to the formation of stable neutral and anionic derivatives. The one-electron reduction of [27] + leads to the formation of a boron containing neutral radical featuring an unusual boron-carbon one-electron π bond. Further reduction of 27• results in the formation of the borataalkene derivative [27]-, which features a formal B=C double bond. The structural changes accompanying the stepwise population of the B-C π-bond are also determined, and this sequential population of B-C π-bonding orbital is also supported by theoretical computations. In order to understand the impact of the cationic nature of these boranes on their oxidative power, three novel cationic boranes ([34] +, [35]2+, and [36] 3+) have been synthesized and their oxidative power were examined via cyclic voltammetry. The CV data of these compounds shows that the reduction potential of these triarylboranes is linearly proportional to the number of the pendant cationic substituents. Substitution of a mesityl group by an Ar N+ group leads to an increase of the reduction potential by 260 mV.

ISBN: 9780549721482Subjects--Topical Terms:

3173556
Inorganic chemistry.
Subjects--Index Terms:

Anion complexation

Synthesis, characterization, anion complexation and electrochemistry of cationic Lewis acids.
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245 1 0 $a Synthesis, characterization, anion complexation and electrochemistry of cationic Lewis acids.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2008
300 $a 204 p.
500 $a Source: Dissertations Abstracts International, Volume: 70-04, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Gabbai, Francois P.
502 $a Thesis (Ph.D.)--Texas A&M University, 2008.
506 $a This item is not available from ProQuest Dissertations & Theses.
520 $a Owing to the favored Coulombic attraction between the ammonium group and anion which stabilizes the B-F/B-CN bond against heterolysis, cationic borane [25]+ has great affinity toward anions than its neutral analog, and is capable of capturing fluoride or cyanide from water under bi-phasic conditions. By placing the fluorophilic silyl group adjacent to an electrophilic carbocation, a novel fluoride sensor [ 45]+ was obtained. Sensing occurs via a fluoride induced methyl migration from the silicon to adjacent electrophilic methylium center which is unprecedented. As a result of its strong fluoride affinity, [ 45]+ is able to react with KF in aqueous media at pH 7.0. The electrochemistry study of these cationic Lewis boranes reveals that the cationic character of these boranes serves to decrease their reduction potential and increase the stability of the resulting radicals. In this part of the research, we have prepared a cationic borane [27] +, which features two reversible reduction waves at -0.86 and -1.56 (vs. Fc/Fc+) corresponding to the formation of stable neutral and anionic derivatives. The one-electron reduction of [27] + leads to the formation of a boron containing neutral radical featuring an unusual boron-carbon one-electron π bond. Further reduction of 27• results in the formation of the borataalkene derivative [27]-, which features a formal B=C double bond. The structural changes accompanying the stepwise population of the B-C π-bond are also determined, and this sequential population of B-C π-bonding orbital is also supported by theoretical computations. In order to understand the impact of the cationic nature of these boranes on their oxidative power, three novel cationic boranes ([34] +, [35]2+, and [36] 3+) have been synthesized and their oxidative power were examined via cyclic voltammetry. The CV data of these compounds shows that the reduction potential of these triarylboranes is linearly proportional to the number of the pendant cationic substituents. Substitution of a mesityl group by an Ar N+ group leads to an increase of the reduction potential by 260 mV.
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653 $a Cationic Lewis acids
653 $a Electrochemistry
653 $a Lewis acids
653 $a Triarylborane
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