ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
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; k-2=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. [Note to reader: Please see article pdf to view this scheme.] © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 523-532, 1998
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
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