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Bowman, Edward (2024) Time-Resolved Spectroscopy of Organometallic Alkane and Silane Intermediates. PhD thesis, University of Nottingham.

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Abstract

Chapter 1

In this Chapter, the history of time-resolved spectroscopic methods is reviewed, with particular focus on IR spectroscopy and XAS spectroscopy. The study of metal carbonyl intermediates, the family of complexes investigated in this Thesis, and the previous investigation of their photochemistry is also reviewed.

Chapter 2

In this Chapter, experimental techniques and spectroscopic apparatus used to perform TRXAS at the APS and to take TRIR measurements at the University of Nottingham are described. Computational methods used to process and produce data in other Chapters of this Thesis are also detailed.

Chapter 3

This Chapter details the development and implementation of a time resolved XAS system on the I18 beamline of the Diamond Light Source synchrotron, including details of the components and adaptation of the setup across multiple experiments. The impact of setup design on signal is described, with quality of the jet, the collinearity of the laser and x-ray beams, and the proximity of the avalanche photodiode (APD) found to be of great importance to producing quality signal.

Chapter 4

In this Chapter, the photolysis of CpRe(CO)3 in alkane and alkyl silane solvents is explored with TRIR and TRXAS. The kinetics of CpRe(CO)3 photolyzed in n-heptane doped with triethyl silane are measured with TRIR. EXAFS data was used to measure the Re-Calkane bond lengths of CpRe(CO)2(n-hexane) (2.61±0.37 Å) and CpRe(CO)2(cyclohexane) (2.52±0.11 Å). The Re-Si bond length for CpRe(CO)2(HSiEt3) was also evaluated, and was found to be 2.45±0.05 Å for the 0 to 10 μs timeframe and 2.42±0.05 Å at the 10 to 30 μs timeframe. These values are within error of computational calculations, but measuring detail sufficient to conclusively determine the activation of C-H or Si-H bonds will require both more extensive calculations and higher quality data than have been obtained in this Thesis.

Chapter 5

This Chapter examines TRIR and TRXAS data for the photolysis of CpMn(CO)3 in alkane and alkyl silane solvents. TRIR has been used to determine the photoproducts of CpMn(CO)3 in n-heptane doped with triethyl silane and established the relationship between the conversion of CpMn(CO)2(n-heptane) to CpMn(CO)2(HSiEt3) and the doped concentration of triethyl silane.

TRXAS has been used to characterize the difference K-edge manganese data arising from photolysis of CpMn(CO)3 to form both an alkane-bound and silane-bound structure. We found evidence that CpMn(CO)2(n-heptane) exists in both the primary carbon bound and secondary carbon bound isomers, and identified characteristic features of carbon binding in a silane-doped alkane solution.

The XANES modelling abilities of both FDMNES and QChem were tested, with both software packages being found to produce qualitatively comparable spectra. This allowed the assignment of select features in the experimental data to alkane or silane binding, illustrating the use of theoretical modelling even in early development.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	George, Michael Dent, Andrew Bartlett, Stuart Besley, Nick
Keywords:	TRIR, time-resolved spectroscopy, XAFS, organometallic intermediates, manganese, rhenium, spectrum analysis
Subjects:	Q Science > QD Chemistry > QD146 Inorganic chemistry
Faculties/Schools:	UK Campuses > Faculty of Science > School of Chemistry
Item ID:	77207
Depositing User:	Bowman, Edward
Date Deposited:	24 Jul 2024 04:40
Last Modified:	24 Jul 2024 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/77207

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