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The gas-phase ion chemistry of substituted silanes

Citation

Murthy, Srihari (1993) The gas-phase ion chemistry of substituted silanes. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:01042013-113332582

Abstract

Ion-molecule reactions in the chlorosilanes, SiH_nCl_(4_n)(n = 0-3), and in phenylsilane have been studied by the technique of Fourier transform ion cyclotron resonance spectrometry.

In Chapter 1, the motivations for studying the gas-phase ion chemistry of substituted silanes as well as brief descriptions of the gas phase ion chemistry of the chlorosilanes and of phenylsilane are presented.

Chapter 2 deals with the gas-phase ion chemistry of the chlorosilanes, SiH_nCl_(4_n)(n = 0-2). Reactions of the chlorosilyl ions with neutral chlorosilanes and with silane as well as the reactions of the silyl ion with neutral chlorosilanes are presented. The chlorosilyl ions participate in Hˉ, Clˉ transfer reactions and disproportionation reactions. The mechanisms of these reactions are discussed. The Claffinities of the chlorosilyl ions, SiH_n Cl_(3_n) + (n = 0-2), lie within a range of 1.2 kcal mol^(-1) and decrease in the order SiH_2Cl^+ > SiHCl_2 + ≈ SiCl_3 ^+. The heats of formation of the chlorosilyl ions are determined.

Chapter 3 deals with the gas-phase ion chemistry of monochlorosilane. The difference in the Hˉ affinities of the ions SiH_2Cl^+ and SiHC1_2 + is determined to be 1.5 ± 0.3 kcal mo^(-1). The Hˉ affinities of the chlorosilyl ions, SiH_n Cl_(3_n) + (n = 0-2), lie within a range of 1.8 kcal mol^(-1) and decrease in the order SiH_2Cl^+ ≈ SiCl_3 + > SiHCl_2^+. Protonated SiH_3Cl is generated by proton transfer from CH_5^+ and is observed to react with SiH3Cl to yield (SiH3)2Cl+.

Chapter 4 deals with the gas-phase ion chemistry of phenylsilane. In analogy with toluene, two (parent – H)^+ cations are produced by the electron impact ionization of phenylsilane. These cations are identified to be the phenylsilyl and the silacycloheptatrienyl cations.

Chapter 5 explores the gas-phase ion chemistry of phenylsilane in great detail. Reactions of the parent and fragment ions (created by electron impact ionization) with neutral phenylsilane and with C_6D_6 are presented. Two structural isomers are identified for the C_6H_8Si^+ cation and three structural isomers are identified for the C_6H_6Si^+ cation. The Hˉ affinity of the phenylsilyl cation is also presented.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Beauchamp, Jesse L.
Thesis Committee:
  • unknown, unknown
Defense Date:24 May 1993
Record Number:CaltechTHESIS:01042013-113332582
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:01042013-113332582
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7369
Collection:CaltechTHESIS
Deposited By: John Wade
Deposited On:04 Jan 2013 22:51
Last Modified:04 Jan 2013 22:51

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