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Reactivity of CpCr(III) N-Heterocyclic Carbene Diiodide Yallits, Emily
Abstract
Chromium complexes are well known for their applications in alkene and alkyne trimerization. In this thesis, a previously synthesized CpCr(NHC)I2 complex (where NHC stands for N-heterocyclic carbene), were investigated for alkyne trimerization. The objective was to optimize the reduction and initial alkyne-coupling steps of the mechanism to isolate a well-defined chromacyclopentadiene complex which could later be used for synthetically applicable alkyne trimerization. Initial attempts to utilize the complex to couple two alkyne substrates appeared promising; however, obstacles in spectral analysis prevented any conclusive characterization of the desired complex. The possibility of bimolecular decomposition with similar complexes reported by Jolly6a led to the synthesis of a novel CpCr(iPr-NHC)Cl with bulkier isopropyl substituents on the NHC ancillary ligand. Applications of CpCr(iPr-NHC)Cl in alkyne trimerization appear to be very promising as the isopropyl substituent likely prevents decomposition and improves the crystalline structure of the compound which is helpful for characterization. A number of other CpCr(L)X2 compounds were also tested for reactivity in alkyne trimerization which illustrated the significance of ancillary ligand electron-donating abilities in this type of reactivity.
Item Metadata
Title |
Reactivity of CpCr(III) N-Heterocyclic Carbene Diiodide
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Creator | |
Date Issued |
2010-05-11
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Description |
Chromium complexes are well known for their applications in alkene and alkyne trimerization. In this thesis, a previously synthesized CpCr(NHC)I2 complex (where NHC stands for N-heterocyclic carbene), were investigated for alkyne trimerization. The objective was to optimize the reduction and initial alkyne-coupling steps of the mechanism to isolate a well-defined chromacyclopentadiene complex which could later be used for synthetically applicable alkyne trimerization. Initial attempts to utilize the complex to couple two alkyne substrates appeared promising; however, obstacles in spectral analysis prevented any conclusive characterization of the desired complex. The possibility of bimolecular decomposition with similar complexes reported by Jolly6a led to the synthesis of a novel
CpCr(iPr-NHC)Cl with bulkier isopropyl substituents on the NHC ancillary ligand. Applications of CpCr(iPr-NHC)Cl in alkyne trimerization appear to be very promising as the isopropyl substituent likely prevents decomposition and improves the crystalline structure of the compound which is helpful for characterization. A number of other CpCr(L)X2 compounds were also tested for reactivity in alkyne trimerization which illustrated the significance of ancillary ligand electron-donating abilities in this type of reactivity.
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Genre | |
Type | |
Language |
eng
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Series | |
Date Available |
2016-11-22
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0048181
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URI | |
Affiliation | |
Campus | |
Peer Review Status |
Unreviewed
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Scholarly Level |
Undergraduate
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Copyright Holder |
Emily N. Yallits
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International