Kinetic study of the reaction of tetramethylplatinum(IV) complexes with acids

Yuichi Kondo, Minako Ishikawa, Koji Ishihara

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    Abstract

    Kinetics for the reaction of [PtMe4(NN)] (NN=1,10-phenanthroline or 2,2′-bipyridine) with HA (HA=formic, acetic, benzoic or salicylic acid) in ethanol, [PtMe4(NN)]+HA→kf[PtMe3(A)(NN)]+CH 4 has been studied at various temperatures and pressures. The rate constants and activation parameters for the reaction are as follows: kf (M-1 s-1) (25 °C)=(54.6±0.5)×10-2, ΔH f (kJ mol-1)=52.7±0.2, ΔS f (J mol-1 K-1) = -73.2±0.8, ΔV f (cm3mol-1) = -8.5±0.5 for the reaction of [PtMe4(phen)] with salicyclic acid; kf (M-1 s-1) (25 °C) = (29.6±0.8) × 10-2, ΔH f (kJ mol-1) = 54.8±2.8, ΔS f (J mol-1 K-1) = -71.8±9.4, ΔV f (cm3 mol-1) = -6.6±1.0 for the reaction of [PtMe4(phen)] with formic acid; kf (M-1 s-1) (25 °C) = (6.56±0.04) × 10-1, ΔH f (kJ mol-1) = 53.9±1.9, ΔS f (J mol-1 K-1) = -87.0±6.3, ΔV f (cm3 mol-1) = -8.2±0.3, kf (M-1 s-1) (in methanol, 25 °C) = (9.14±0.04) × 10-2, ΔV f (cm3 mol-1) (in methanol) = -15.1±1.6 for the reaction of [PtMe4(phen)] with benzoic acid; kf (M-1 s-1) (25 °C) = (2.49±0.02) × 10-2, ΔH f (kJ mol-1)=52.4±1.8, ΔS f (J mol-1 K-1) = -99.6±5.8, ΔV f (cm3 mol-1) = -10.5±0.5 for the reaction of [PtMe4(phen)] with acetic acid; kf (M-1 s-1) (25 °C) = (25.6±0.4) × 10-2, ΔH f (kJ mol-1 ) = 49.8±5.0, ΔS f (J mol-1 K-1) = -89.4±16.7, ΔV f (cm3 mol-1) = -12.2±0.4 for the reaction of [PtMe4(bipy)] with formic acid; kf (M-1 s-1) (25 °C) = (1.95±0.04) × 10-2, ΔH f (kJ mol-1) = 54.7±3.0, ΔS f (J mol-1 K-1) = -93.7±10.0, ΔV f (cm3 mol-1) = -11.6±1.0 for the reaction of [PtMe4(bipy) ] with acetic acid. A linear free energy relationship holds between log kf and pKa of HA. The negative values of volume and entropy of activation and a large deuterium kinetic isotope effect strongly indicate that the reaction proceeds with an SE2 mechanism.

    Original languageEnglish
    Pages (from-to)81-85
    Number of pages5
    JournalInorganica Chimica Acta
    Volume241
    Issue number2
    DOIs
    Publication statusPublished - 1996 Jan 15

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    Keywords

    • Activation volume
    • Kinetic isotope effect
    • Kinetics and mechanism
    • Platinum complexes
    • Tetramethyl complexes

    ASJC Scopus subject areas

    • Biochemistry
    • Inorganic Chemistry
    • Physical and Theoretical Chemistry
    • Materials Chemistry

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