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Kinetic study of the ligand substitution on the trimethylplatinum(iv) complexes with unidentate ligands
Author(s) -
Kondo Yuichi,
Oda Yumi,
Ishihara Koji
Publication year - 1998
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1998)30:8<523::aid-kin1>3.0.co;2-u
Subject(s) - chemistry , denticity , substitution (logic) , ligand (biochemistry) , kinetic energy , substitution reaction , kinetics , stereochemistry , crystallography , medicinal chemistry , crystal structure , biochemistry , receptor , physics , quantum mechanics , computer science , programming language
Ligand substitution kinetics for the reaction [Pt IV Me 3 (X)(NN)]+NaY=[Pt IV Me 3 (Y)(NN)]+NaX, where NN=bipy or phen, X=MeO − , CH 3 COO − , or HCOO − , and Y=SCN − or N 3 − , has been studied in methanol at various temperatures. The kinetic parameters for the reaction are as follows. The reaction of [PtMe 3 (OMe)(phen)] with NaSCN: k 1 =36.1±10.0 s −1 ; Δ H 1 ≠ =65.9±14.2 kJ mol −1 ; Δ S 1 ≠ =6±47 J mol −1 K −1 ; k −2 =0.0355±0.0034 s −1 ; Δ H −2 ≠ =63.8±1.1 kJ mol −1 ; Δ S −2 ≠ =−58.8±3.6 J mol −1 K −1 ; and k −1 / k 2 =148±19. The reaction of [PtMe 3 (OAc)(bipy)] with NaN 3 : k 1 =26.2±0.1 s −1 ; Δ H 1 ≠ =60.5±6.6 kJ mol −1 ; Δ S 1 ≠ =−14±22 J mol −1 K −1 ; k −2 =0.134±0.081 s −1 ; Δ H −2 ≠ =74.1±24.3 kJ mol −1 ; Δ S −2 ≠ =−10±82 J mol −1 K −1 ; and k −1 / k 2 =0.479±0.012. The reaction of [PtMe 3 (OAc)(bipy)] with NaSCN: k 1 =26.4±0.3 s −1 ; Δ H 1 ≠ =59.6±6.7 kJ mol −1 ; Δ S 1 ≠ =−17±23 J mol −1 K −1 ; k −2 =0.174±0.200 s −1 ; Δ H −2 ≠ =62.7±10.3 kJ mol −1 ; Δ S −2 ≠ =−48±35 J mol −1 K −1 ; and k −1 / k 2 =1.01±0.08. The reaction of [PtMe 3 (OOCH)(bipy)] with NaN 3 : k 1 =36.8±0.3 s −1 ; Δ H 1 ≠ =66.4±4.7 kJ mol −1 ; Δ S 1 ≠ =7±16 J mol −1 K −1 ; k −2 =0.164±0.076 s −1 ; Δ H −2 ≠ =47.0±18.1 kJ mol −1 ; Δ S −2 ≠ =−101±61 J mol −1 K −1 ; and k −1 / k 2 =5.90±0.18. The reaction of [PtMe 3 (OOCH)(bipy)] with NaSCN: k 1 =33.5±0.2 s −1 ; Δ H 1 ≠ =58.0±0.4 kJ mol −1 ; Δ S 1 ≠ =−20.5±1.6 J mol −1 K −1 ; k −2 =0.222±0.083 s −1 ; Δ H −2 ≠ =54.9±6.3 kJ mol −1 ; Δ S −2 ≠ =−73.0±21.3 J mol −1 K −1 ; and k −1 / k 2 =12.0±0.3. Conditional pseudo‐first‐order rate constant k 0 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