Radio and Microwave Spectroscopic Studies of Some Inorganic Solids

Dalgleish, William Henry (1975) Radio and Microwave Spectroscopic Studies of Some Inorganic Solids. PhD thesis, University of Glasgow.

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Abstract

The thesis deals with some chemical applications of nuclear quadrupole resonance spectroscopy and electron paramagnetic resonance spectroscopy, to the study of some inorganic solids. It is divided into two main parts which are summarised separately below. PART I .The first part of the thesis is devoted to chlorine-35 nuclear quadrupole resonance investigations of some substituted chloro-cyclotriphosphazenes and some cyclodiphosphazanes. The basic electrostatic interactions of nuclear quadrupole resonance are discussed in Chapter I, with particular reference to the chlorine -35 nucleus, which has a nuclear spin quantum number I of 3/2. The way in which quadrupole resonance spectra can be interpreted to obtain information about bonding in chemical compounds is discussed, and the spectrometer used in carrying out this work is briefly described. In Chapter II the chlorine-35 nuclear quadrupole resonance spectra of a series of derivatives of hexachlorocyclotriphosphazatriene, N3P3Cl6, are investigated in order to assess the usefulness of this technique in obtaining structural information on the cyclophosphazenes. N. q. r. frequencies characteristic of =PCl2, = PCINR2, =PClPh and = PCI (N = PR3) groups occur in the ranges 26-29, 22-25, 23-25 and 23. 5-25. 5 M. Hz. respectively. The characteristic frequency ranges of the last three groups overlap, and so these functional groups cannot be distinguished by simply measuring the chlorine-35 nuclear quadrupole resonance frequencies. Cis -and trans -isomers may be distinguished by their resonance frequencies, by comparing the range of frequencies observed, but only when results for both isomers are available. Chapter III is concerned with nuclear quadrupole resonance studies of the related species, the cyclodiphosphazanes, (Cl3PNR)2. It is found that nuclear quadrupole resonance spectroscopy can be used in three ways to distinguish between axial and equatorial chlorine atoms in these compounds; the chlorine-35 n. q. r. frequencies are different, the temperature coefficients of these frequencies are different, and the pressure coefficients of these frequencies are different. The characteristic frequencies are determined essentially by the differences in the degree of ionic character associated with axial and equatorial bonds in the trigonal bipyramidal environment, while the characteristic effects of temperature and pressure on these frequencies originate essentially in the bending modes of vibration which involve the P -Cl fragments in the chlorocyclodiphosphazanes. It is concluded that the effects of pressure changes and temperature changes on the chlorine -35 n. q. r. frequencies in other P-Cl systems should be characteristic of these systems, and these ideas are applied to the chlorocyclotriphosphazatrienes in Chapter IV, where the chlorine-35 n. q. r. spectra of N3P3Cl6 and N3P3Cl5NHPri have been extensively investigated. PART II The second part of the thesis is concerned with electron paramagnetic resonance spectroscopy. In Chapter V the basic theory of electron paramagnetic resonance spectroscopy is discussed, with particular reference to transition metal complexes containing one unpaired electron. In Chapter VI the available electron paramagnetic resonance data for the pseudotetrahedral vanadium (IV) complex (pi-C5H5)VCl2 is reviewed, and the reasons for the disagreement between the various published studies are discussed. In an attempt to resolve this disagreement, a synthesis of the closely related complex (CH2)3(C5H4)2VCl2 has been developed, and the EPR spectra of this compound in both solution and glass phases are reported and analysed. In the course of this preparative reaction it is found that vanadium tetrachloride is present in tetrahydrofuran solutions as an adduct with tetrahydrofuran, and the EPR spectrum of this adduct, VCl4. 2 THF, is also reported in Chapter VI. Attempts to purify (CH2)3(C5H4)2VCI2 by sublimation result in the formation of a further paramagnetic species, which has not been characterised. This compound is believed to be produced by a rearrangement reaction of (CH2)3 (C5H4)2 VCl2.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Analytical chemistry
Date of Award: 1975
Depositing User: Enlighten Team
Unique ID: glathesis:1975-78704
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:00
Last Modified: 30 Jan 2020 15:00
URI: http://theses.gla.ac.uk/id/eprint/78704

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