Reaction Mechanism for Olefin Exchange at Chloro Ethene Complexes of Platinum(II)
(1999) In Inorganic Chemistry 38(6). p.1233-1238- Abstract
- Synopsis In methanol solutions of Zeise's salt, the parent complex [PtCl3(C2H4)]- as well as its solvolysis product, trans-[PtCl2(C2H4)(MeOH)], exchange rapidly with free ethene. The olefin exchange process, which is largely entropy controlled, involves the substitution labile site trans to the coordinated ethene. Abstract Complex equilibria in methanol/chloroform/dichloromethane solutions containing Zeise's anion, [PtCl3(C2H4)]- (1), the solvento species, trans-[PtCl2(C2H4)(MeOH)] (2), and the dinuclear complex, trans-[PtCl2(C2H4)]2 (3), have been studied by UV−vis, 1H, and 195Pt NMR spectroscopy, giving average values of KCl = (1.6 ± 0.2)103 M-1 and KS =... (More)
- Synopsis In methanol solutions of Zeise's salt, the parent complex [PtCl3(C2H4)]- as well as its solvolysis product, trans-[PtCl2(C2H4)(MeOH)], exchange rapidly with free ethene. The olefin exchange process, which is largely entropy controlled, involves the substitution labile site trans to the coordinated ethene. Abstract Complex equilibria in methanol/chloroform/dichloromethane solutions containing Zeise's anion, [PtCl3(C2H4)]- (1), the solvento species, trans-[PtCl2(C2H4)(MeOH)] (2), and the dinuclear complex, trans-[PtCl2(C2H4)]2 (3), have been studied by UV−vis, 1H, and 195Pt NMR spectroscopy, giving average values of KCl = (1.6 ± 0.2)103 M-1 and KS = (0.16 ± 0.02) M-1 for the equilibrium constants between 2 and 1 and 3 and 2, respectively. The bridged complex 3 is completely split into monomeric solvento complexes 2 in methanol and in chloroform or dichloromethane solutions with [MeOH] > 0.5 M. Ethene exchange at the mononuclear complexes 1 and 2 was studied by 1H NMR line-broadening experiments in methanol-d4. Observed overall exchange rate constants decrease with an increase in free chloride concentration due to the displacement of the rapid equilibrium between 1 and 2 toward the more slowly exchanging parent chloro complex 1. Ethene exchange rate constants at 298 K for complexes 1 and 2 are kex1 = (2.1 ± 0.1)103 M-1 s-1and kex2 = (5.0 ± 0.2)105 M-1 s-1, respectively, with corresponding activation parameters ΔH1⧧ = 19.1 ± 0.3 kJ mol-1, ΔS1⧧ = −117 ± 1 J K-1 mol-1, ΔH2⧧ = 10.2 ± 0.4 kJ mol-1, and ΔS2⧧ = −102 ± 2 J K-1 mol-1. The activation process is largely entropy controlled; the enthalpy contributions only amounting to ≈30% of the free energy of activation. Ethene exchange takes place via associative attack by the entering olefin at the labile site trans to the coordinated ethene, which is either occupied by a chloride or a methanol molecule in the ground state. The intimate mechanism might involve a two-step process via trans-[PtCl2(C2H4)2] in steady state or a concerted process via a pentacoordinated transition state with two ethene molecules bound to the platinum(II) (Less)
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https://lup.lub.lu.se/record/4b9aa62d-d166-4618-bd4c-4ed822330e62
- author
- Plutino, Maria R. ; Otto, Stefanus ; Roodt, Andreas and Elding, Lars Ivar LU
- organization
- publishing date
- 1999-03-05
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Olefin exchange, Zeise's anion, Platinum(II) olefin complexes, Reaction mechanism, Fast kinetics, Activation parameters
- in
- Inorganic Chemistry
- volume
- 38
- issue
- 6
- pages
- 6 pages
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- scopus:0000978933
- ISSN
- 1520-510X
- DOI
- 10.1021/ic981020t
- language
- English
- LU publication?
- yes
- id
- 4b9aa62d-d166-4618-bd4c-4ed822330e62
- date added to LUP
- 2016-12-17 19:04:21
- date last changed
- 2022-01-30 08:32:46
@article{4b9aa62d-d166-4618-bd4c-4ed822330e62,
abstract = {{Synopsis In methanol solutions of Zeise's salt, the parent complex [PtCl3(C2H4)]- as well as its solvolysis product, <i style="font-family: Helvetica, Arial, sans-serif; font-size: 13px;">trans</i>-[PtCl2(C2H4)(MeOH)], exchange rapidly with free ethene. The olefin exchange process, which is largely entropy controlled, involves the substitution labile site trans to the coordinated ethene. Abstract Complex equilibria in methanol/chloroform/dichloromethane solutions containing Zeise's anion, [PtCl3(C2H4)]- (1), the solvento species, trans-[PtCl2(C2H4)(MeOH)] (2), and the dinuclear complex, trans-[PtCl2(C2H4)]2 (3), have been studied by UV−vis, 1H, and 195Pt NMR spectroscopy, giving average values of KCl = (1.6 ± 0.2)103 M-1 and KS = (0.16 ± 0.02) M-1 for the equilibrium constants between 2 and 1 and 3 and 2, respectively. The bridged complex 3 is completely split into monomeric solvento complexes 2 in methanol and in chloroform or dichloromethane solutions with [MeOH] > 0.5 M. Ethene exchange at the mononuclear complexes 1 and 2 was studied by 1H NMR line-broadening experiments in methanol-d4. Observed overall exchange rate constants decrease with an increase in free chloride concentration due to the displacement of the rapid equilibrium between 1 and 2 toward the more slowly exchanging parent chloro complex 1. Ethene exchange rate constants at 298 K for complexes 1 and 2 are kex1 = (2.1 ± 0.1)103 M-1 s-1and kex2 = (5.0 ± 0.2)105 M-1 s-1, respectively, with corresponding activation parameters ΔH1⧧ = 19.1 ± 0.3 kJ mol-1, ΔS1⧧ = −117 ± 1 J K-1 mol-1, ΔH2⧧ = 10.2 ± 0.4 kJ mol-1, and ΔS2⧧ = −102 ± 2 J K-1 mol-1. The activation process is largely entropy controlled; the enthalpy contributions only amounting to ≈30% of the free energy of activation. Ethene exchange takes place via associative attack by the entering olefin at the labile site trans to the coordinated ethene, which is either occupied by a chloride or a methanol molecule in the ground state. The intimate mechanism might involve a two-step process via trans-[PtCl2(C2H4)2] in steady state or a concerted process via a pentacoordinated transition state with two ethene molecules bound to the platinum(II)}},
author = {{Plutino, Maria R. and Otto, Stefanus and Roodt, Andreas and Elding, Lars Ivar}},
issn = {{1520-510X}},
keywords = {{Olefin exchange; Zeise's anion; Platinum(II) olefin complexes; Reaction mechanism; Fast kinetics; Activation parameters}},
language = {{eng}},
month = {{03}},
number = {{6}},
pages = {{1233--1238}},
publisher = {{The American Chemical Society (ACS)}},
series = {{Inorganic Chemistry}},
title = {{Reaction Mechanism for Olefin Exchange at Chloro Ethene Complexes of Platinum(II)}},
url = {{http://dx.doi.org/10.1021/ic981020t}},
doi = {{10.1021/ic981020t}},
volume = {{38}},
year = {{1999}},
}