Browsing by Author "Reddy, Desigan"

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    An investigation of comparative substitution behavior of bifunctional trans-platinum(II) complexes with symmetric and asymmetric alkylamine ligands
    (International Journal of Chemical Kinetics, 2020-08-04) Jaganyi, Deogratius; Reddy, Desigan; Olusegun, Moses Ariyo
    This study was undertaken to investigate the comparative substitution behavior of mononuclear trans-platinum(II) complexes with symmetric and asymmetric amine ligands. The rate of substitution of the aqua moeities from the complexes trans-[Pt(NH3)2(H2O)2](ClO4)2 (tPt), trans-[Pt(NH3)(NH2C2H5)(H2O)2](ClO4)2 (tPt2H2O), trans-[Pt(NH3)(NH2C3H7)(H2O)2](ClO4)2 (tPt3H2O), [trans-Pt(OH2)2(NH2CH3)2](ClO4)2 (tPtM), and [trans-Pt(OH2)2{NH2CH(CH3)2}2](ClO4)2 (tPtR), by three nucleophiles, namely thiourea (TU), 1,3-dimethylthiourea (DMTU), and 1,1,3,3-tetramethylthiourea (TMTU) was studied under pseudo–first-order conditions as a function of concentration and temperature by stopped-flow spectrophotometry. All the substitution reactions of each of the trans-platinum(II) complexes proceeds by a stepwise mechanism involving rate-determining substitution of the first aqua ligand followed by a fast second substitution step, without any intermediates formed. The reactions were second order overall (rate = kobs[complex] where kobs = k2[nucleophile]), first order in both [complex] and [nucleophile]. The reactivity of the complexes was essentially governed by both steric and electronic factors. Comparing the second-order rate constants for the substitution reactions of the mononuclear diaqua trans-platinum(II) complexes with the thiourea-based nucleophiles, the observed trend follows: tPt > tPt2H2O > tPtM > tPt3H2O > tPtR. This reactivity trend is consistent with the pKa values obtained for the first deprotonation step. The reactivity of the nucleophiles with the complexes decreases with an increase in steric demand in the following order: TU > DMTU > TMTU. The low positive values of activation enthalpy and large negative values of activation entropy indicate an associative mechanism of substitution in all the complexes. The computational modeling using density functional theory calculations was employed to provide theoretical interpretation of kinetic data.
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    Correction to: A kinetic investigation of mononuclear trans-platinum(II) complexes with mixed amine ligands
    (Springer link, 2020-03-12) Jaganyi, Deogratius; Reddy, Desigan; Olusegun, Moses Ariyo
    The article “A kinetic investigation of mononuclear trans-platinum(II) complexes with mixed amine ligands”, written by “Moses Ariyo Olusegun, Desigan Reddy and Deogratius Jaganyi”, was originally published electronically on the publisher’s internet portal https://link.springer.com/article/10.1007/s11243-020-00381-0 on 12 March 2020 with open access. With the author(s)’ decision to step back from Open Choice, the copyright of the article changed on 20 April 2020 to ©Springer Nature Switzerland AG 2020 and the article is forthwith distributed under the terms of copyright.