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Metal(III)-water interactions

Tregenna-Piggott, Philip Louis William; (1994) Metal(III)-water interactions. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

This thesis is devoted to the study of metal(III)-water interactions by a variety of physical techniques. Studies are undertaken in the solid state where the tervalent hexa-aqua-cation is held rigidly within the lattice, thus facilitating its study. The RbMᴵᴵᴵ(SO₄)₂.12H₂O alums, where Mᴵᴵᴵ is Al, Ga, In, Ti, V, Cr, and Fe, have been characterised by Raman spectroscopy. The Ti and V rubidium alums are of a different structural modification to the other alums studied. This is related to a change in the mode of water co-ordination leading to a larger trigonal field stabilisation energy for the Ti and V hexa-aqua-cations. The Raman spectra of the RbTi(SO₄)₂.12H₂O alum are anomalous. Soft modes are observed indicating the onset of a phase transition. The Raman spectra are interpreted in conjunction with the published EPR and magnetic data for the [Ti(OH₂)₆]³⁺ cation. A model in which the [Ti(OH₂)₆]³⁺ cation is subject to a dynamic Jahn-Teller distortion, freezing out into a static distortion at temperatures approaching 4 K, is proposed. A polarised neutron diffraction experiment has been performed on CsMo(SO₄)₂.12D₂O. This is the first report of such a study for any tervalent hexa-aqua-cation. Information on the spatial spin distribution within the [Mo(OD₂)₆]³⁺ cation is obtained. Spin density is found to occupy t2g-like orbitals on the metal with some spin transferred to the ligand where it is concentrated in a molecular orbital normal to the plane of the water molecule. Negative spin is also found in the molybdenum-oxygen bonding region indicative of electron correlation effects. These observations are interpreted in terms of simple concepts of chemical bonding.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Metal(III)-water interactions
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Pure sciences; Hexa-aqua-cation
URI: https://discovery.ucl.ac.uk/id/eprint/10106214
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