Research Articles (Chemistry)

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Browsing Research Articles (Chemistry) by Subject "DFT"

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    Density functional theory calculated data of the iodomethane oxidative addition to oligothiophene-containing rhodium complexes – importance of dispersion correction
    (Elsevier, 2021) Mateyise, Nandisiwe Ghandi Sibongile; Conradie, Jeanet; Conradie, Marrigje M.
    Electronic and free energy data of density functional theory calculated optimized geometries of the reactants, transition state of the oxidative addition reaction and different reaction products of the [Rh(RCOCHCOCF 3 )(CO)(PPh 3 )] + CH 3 I reactions (R = C 4 H 3 S, C 4 H 3 S-C 4 H 2 S and C 4 H 3 S-C 4 H 2 S-C 4 H 2 S) are presented to illustrate the influence of the amount of thiophene groups, the implicit solvent and dispersion correction on the calculated energies. All calculations were done with the B3LYP functional, in gas as well as in solvent phase, with and without dispersion correction. The data can save computational chemists time when choosing an appropriate method to calculate reaction energies of oxidative addition reactions. Detailed knowledge of energies involved in the oxidative addition reaction of methyl iodide to rhodium complexes have an important implication in catalysis, for example the Monsanto process where methanol is converted to acetic acid catalysed by a rhodium complex. For more insight in the reported data, see the related research article “Synthesis, characterization, electrochemistry, DFT and kinetic study of the oligothiophene-containing complex [Rh((C 4 H 3 S- C 4 H 2 S)COCHCOCF 3 )(CO)(PPh 3 )]”, published in Polyhedron.
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    Kinetic study of the oxidative addition reaction between methyl iodide and [Rh(imino-β-diketonato)(CO)(PPh)3] complexes, utilizing UV–vis, IR spectrophotometry, NMR spectroscopy and DFT calculations
    (MDPI, 2022) Ferreira, Hendrik; Conradie, Marrigje Marianne; Conradie, Jeanet
    The oxidative addition of methyl iodide to [Rh(β-diketonato)(CO)(PPh)3] complexes, as modal catalysts of the first step during the Monsanto process, are well-studied. The β-diketonato ligand is a bidentate (BID) ligand that bonds, through two O donor atoms (O,O-BID ligand), to rhodium. Imino-β-diketones are similar to β-diketones, though the donor atoms are N and O, referred to as an N,O-BID ligand. In this study, the oxidative addition of methyl iodide to [Rh(imino-β-diketonato)(CO)(PPh)3] complexes, as observed on UV–Vis spectrophotometry, IR spectrophotometry and NMR spectrometry, are presented. Experimentally, one isomer of [Rh(CH3COCHCNPhCH3)(CO)(PPh3)] and two isomers of [Rh(CH3COCHCNHCH3)(CO)(PPh3)] are observed—in agreement with density functional theory (DFT) calculations. Experimentally the [Rh(CH3COCHCNPhCH3)(CO)(PPh3)] + CH3I reaction proceeds through one reaction step, with a rhodium(III)-alkyl as the final reaction product. However, the [Rh(CH3COCHCNHCH3)(CO)(PPh3)] + CH3I reaction proceeds through two reaction steps, with a rhodium(III)-acyl as the final reaction product. DFT calculations of all the possible reaction products and transition states agree with experimental findings. Due to the smaller electronegativity of N, compared to O, the oxidative addition reaction rate of CH3I to the two [Rh(imino-β-diketonato)(CO)(PPh)3] complexes of this study was 7–11 times faster than the oxidative addition reaction rate of CH3I to [Rh(CH3COCHCOCH3)(CO)(PPh3)].
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    Polypyridyl copper complexes as dye sensitizer and redox mediator for dye-sensitized solar cells
    (Elsevier, 2021) Conradie, Jeanet
    Developments on the application of polypyridyl-based copper complexes in dye-sensitized solar cells (DSSCs) are briefly discussed in this mini review. Copper complexes in solar cells are special in that they can be used either as dye sensitizer and/or as redox mediator (redox couple) in dye-sensitized solar cells (DSSCs). Both the abundance and low cost of copper motivates research on the use of copper complexes, as cheaper and non-toxic alternative to the mostly used iodide/triiodide (I- /I3- ) electrolyte redox couple, and the expensive and rare rutheniumbased dyes of good performance, which currently are best known.
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    Review of DFT-simulated and experimental electrochemistry properties of the polypyridyl Row-1 Mn, Fe & Co, and Group-8 Fe, Ru and Os MLCT complexes
    (Elsevier, 2022) Von Eschwege, Karel G.; Conradie, Jeanet
    Ruthenium had up to date been pivotal in electro- and photocatalytic applications involving reduction of CO2 and H2O, and dye-sensitized solar cells. Commercial applications would seek use of earth-abundant metals instead. Towards this goal, it is key to review the synthesis, electrochemical and spectroscopical properties of associated metal-to-ligand charge transfer complexes of row-4 (Mn, Fe & Co) and column-8 (Fe, Ru & Os). The present report is limited to data obtained under exactly similar conditions, providing scientifically valid correlations. Only tris-coordinated bipyridyl and phenanthroline complex derivatives are considered, being representative of catalysts and dyes traditionally used in the above-mentioned fields. The accuracy of theoretical DFT techniques to simulate complex properties is highlighted.