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Electrochemical and Theorectical Studies of Oxidation-Reduction Reactions of Platinum (II) and (IV) Complexes

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Title: Electrochemical and Theorectical Studies of Oxidation-Reduction Reactions of Platinum (II) and (IV) Complexes
Authors: Lai, Chiu-Nan
Advisor: Hubbard, Arthur
Issue Date: 15 Jan 2014
Publisher: University of Hawaii at Manoa
Abstract: Electrochemical interconversion of complexes of Pt(II) and Pt(IV) is accelerated by the presence of halideions and halogen ligands. Semi-empirical MO Calculation and spectra data suggest that oxidation of PT(II) involves the transfer of electron density from filled orbitals of the complex, such as a1g( σ*) [5dz2] through unfilled orbitals of the compact layer or the electrode surface. Similarly, reduction of Pt(IV) complexes, for instance those of D4h symmetry such as PtIVL4X4, may proceed through interaction of a low-energy unfilled orbital if Pt(IV), such as a1g( σ*), with filled orbitals of the compact layer or the electrode surface by way of the unfilled ndz2 orbital of a bridging halide ligand. Pt(II) complexes containing unsaturated ligands such as CN­ of SCN- are less rapidly oxidized than their saturated analogs. Evidence is presented that unsaturated ligands having suitable π* orbitals stabilize the particular orbitals from which electron density is removed in the rate-limiting step. Pt(IV) complexes having a CN- ligand situated trans to a lone halide ligand are reduced with difficulty, whereas complexes having a trans-pair of halide ligands react readily; this trend is consistent with stabilization of the leaving trans-axis and de-stabilization of the interaction between the bridging ligand and the electrode surface due to d-π* back-bonding between Pt( IV) and the unsaturated ligand. A Molecular Orbital approach to the study of electrochemical reactions is presented. The calculated electrochemical rate constants are compared to experimental values obtained at thin-layer electrode. The qualitative trends agree in general. Suggestion for improvement of the calculation also included.
Pages/Duration: vii, 41 pages
Rights: All UHM Honors Projects are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections:Honors Projects for Chemistry

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