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Kinetics and mechanistic investigation of the substitution from dinuclear Pt(II) complexes bridged by N,N’-bis(2-pyridylcarboxamide)phenylenediamines

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dc.contributor.authorMambanda, Allen
dc.contributor.authorJagany, Deogratius
dc.contributor.authorPapo, Tshephiso
dc.date.accessioned2024-06-12T07:06:33Z
dc.date.available2024-06-12T07:06:33Z
dc.date.issued2024-01-08
dc.description.abstractThe rates of substitution of the chloride ligand in dinuclear complexes, [Pt2(N,N'-bis(2-pyridylcarboxamide)-1,3-phenylenediamine)Cl4] (1), [Pt2(N,N'-bis(2-pyridylcarboxamide)-1,4-phenylenediamine)Cl4] (2), [Pt2(N,N'-bis(3-isoquinolylcarboxamide)-1,3-phenylenediamine)Cl4] (3) and [Pt2(N,N'-bis(3-isoquinolylcarboxamide)-1,4-phenylenediamine)Cl4] (4), by three bio-relevant nucleophiles, thiourea (TU), N,N-dimethylthiourea (DMTU) and N,N,N’,N’-tetramethylthiourea (TMTU), were investigated. The mononuclear analogue [Pt(N-phenylpyridine-2-carboxamide)Cl2] (5) was included to compare the results. The kinetics of the reactions were studied under pseudo first-order conditions in a methanol solution (I = 0.1 M LiCl) as a function of concentration and temperature using the stopped-flow spectrophotometer. The observed pseudo first-order rate constants for the substitution reactions of all the complexes were calculated from two well-separated steps and obey the rate law kobs (1st/2nd) = k2 (1st/2nd)[Nu]. The reactivity of the complexes decreases in the order 2 > 1 > 4 > 3 > 5. The conformational symmetry of the complexes as controlled by the phenylenediamine bridges, steric hindrance due to the bridges as well as the σ-donor capacity of the coordinated groups around the metal centers influence the reactivity of the dinuclear complexes. The low enthalpy (ΔH#) and negative intrinsic entropy (ΔS#) values support an associative mechanism of substitution. The kinetic data are supported by DFT calculations.
dc.identifier.urihttps://doi.org/10.1080/00958972.2023.2299962
dc.identifier.urihttps://erepository.mku.ac.ke/handle/123456789/5878
dc.language.isoen
dc.publisherJournal of Cordination chemistry
dc.subjectPlatinum complexes
dc.subjectcarboxamide
dc.subjectsubstitution reactions
dc.subjectmechanistic
dc.titleKinetics and mechanistic investigation of the substitution from dinuclear Pt(II) complexes bridged by N,N’-bis(2-pyridylcarboxamide)phenylenediamines
dc.typeArticle
dspace.entity.typePublication
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