Kinetic study of the ligand substitution on the trimethylplatinum(IV) complexes with unidentate ligands

Yuichi Kondo, Yumi Oda, Koji Ishihara

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2 Citations (Scopus)

Abstract

Ligand substitution kinetics for the reaction [PtIVMe3(X)(NN)] + NaY = [PtIVMe3(Y)(NN)] + NaX, where NN = bipy or phen, X = MeO-, CH3COO-, or HCOO-, and Y = SCN- or N3-, has been studied in methanol at various temperatures. The kinetic parameters for the reaction are as follows. The reaction of [PtMe3(OMe)(phen)] with NaSCN: k1 = 36.1 ± 10.0 s-1; ΔH1 = 65.9 ± 14.2 kj mol-1; ΔS1 = 6 ± 47 J mol-1 K-1; k2 = 0.0355 ± 0.0034 s-1; ΔH-2 = 63.8 ± 1.1 kJ mol-1; ΔS-2 = -58.8 ± 3.6 J mol-1 K-1; and k-1/k2 = 148 ± 19. The reaction of [PtMe3(OAc)(bipy)] with NaN3: k1 = 26.2 ± 0.1 s-1; ΔH1 = 60.5 ± 6.6 kJ mol-1; ΔS1 = -14 ± 22 J mol-1K-1; k-2 = 0.134 ± 0.081 s-1; ΔH-2 = 74.1 ± 24.3 kJ mol-1; ΔS-2 = -10 ± 82 J mol-1K-1; and k-1/k2 = 0.479 ± 0.012. The reaction of [PtMe3(OAc)(bipy)] with NaSCN; k1 = 26.4 ± 0.3 s-1; ΔH1 = 59.6 ± 6.7 kJ mol-1; ΔS1 = -17 ± 23 J mol-1K-1; k-2 = 0.174 ± 0.200 s-1; ΔH-2 = 62.7 ± 10.3 kJ mol-1; ΔS-2 = -48 ± 35 J mol-1K-1 and k-1/k2 = 1.01 ± 0.08. The reaction of [PtMe3(OOCH)(bipy)] with NaN3: k1 = 36.8 ± 0.3 s-1; ΔH1 = 66.4 ± 4.7 kJ mol-1; ΔS1 = 7 ± 16 J mol-1K-1; k-2 = 0.164 ± 0.076 s-1; ΔH-2 = 47.0 ± 18.1 kJ mol-1; ΔS-2 = -101 ± 61 J mol-1 K-1; and k-1/k2 = 5.90 ± 0.18. The reaction of [PtMe3(OOCH)(bipy)] with NaSCN: k1 = 33.5 ± 0.2 s-1; ΔH1 = 58.0 ± 0.4 kJ mol-1; ΔS1 = -20.5 ± 1.6 J mol-1 K-1; k-2 = 0.222 ± 0.083 s-1; ΔH-2 = 54.9 ± 6.3 kJ mol-1; ΔS-2 = -73.0 ± 21.3 J mol-1 K-1; and k-1/k2 = 12.0 ± 0.3. Conditional pseudo-first-order rate constant k0 increased linearly with the concentration of NaY, while it decreased drastically with the concentration of NaX. Some plausible mechanisms were examined, and the following mechanism was proposed.>

Original languageEnglish
Pages (from-to)523-532
Number of pages10
JournalInternational Journal of Chemical Kinetics
Volume30
Issue number8
DOIs
Publication statusPublished - 1998 Jan 1

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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