Kinetics and mechanism for reduction of trans-dichlorotetracyanoplatinate(IV) by tetraammineplatinum(II) and bis(ethylenediammine)platinum(II)
(1998) In Inorganica Chimica Acta 1998(282). p.55-60- Abstract
- Reduction of trans-[Pt(CN)(4)Cl-2](2-) by [Pt(NH3)(4)](2+) and [Pt(en)(2)](2+) was studied at 25 degrees C in the range 0 less than or equal to [Cl-] less than or equal to 0.4 M by use of stopped-flow spectrophotometry. The stoichiometry [Pt(IV)]:[Pt(II)] is 1:1. Rapid-scan spectra show clear-cut isosbestic points, indicating that no reaction intermediates are accumulated to a significant amount. For pseudo first-order conditions with excess Pt(II), the observed rate constants can be expressed as k(obsd)=(k(1)+k(2)K[Cl-])[Pt(II)], with k(1)=400+/-10 and (3.3+/-0.4)x10(3)M(-1)s(-1), and k(2)K= (3.25 +/-0.04) X 10(4) and (6.67 +/-0.07) x 10(5) M-2 s(-1) at 25 degrees C for reduction by [Pt(NH3)(4)](2+) and [Pt(en)(2)](2+), respectively. The... (More)
- Reduction of trans-[Pt(CN)(4)Cl-2](2-) by [Pt(NH3)(4)](2+) and [Pt(en)(2)](2+) was studied at 25 degrees C in the range 0 less than or equal to [Cl-] less than or equal to 0.4 M by use of stopped-flow spectrophotometry. The stoichiometry [Pt(IV)]:[Pt(II)] is 1:1. Rapid-scan spectra show clear-cut isosbestic points, indicating that no reaction intermediates are accumulated to a significant amount. For pseudo first-order conditions with excess Pt(II), the observed rate constants can be expressed as k(obsd)=(k(1)+k(2)K[Cl-])[Pt(II)], with k(1)=400+/-10 and (3.3+/-0.4)x10(3)M(-1)s(-1), and k(2)K= (3.25 +/-0.04) X 10(4) and (6.67 +/-0.07) x 10(5) M-2 s(-1) at 25 degrees C for reduction by [Pt(NH3)(4)](2+) and [Pt(en)(2)](2+), respectively. The mechanism involves two parallel reaction pathways. The analysis of the ionic strength dependence of k(1), together with the rapid-scan spectra, implies that reduction of trans-[Pt(CN)(4)Cl-2](2-) by these Pt(II) complexes takes place directly via chloride-bridged transition states of the type [H2O ... Pt-II... Cl ... Pt-IV... Cl](not equal) for the k(1) pathway, or [Cl ... Pt-II... Cl ... Pt-IV... Cl](not equal) for the k(2) path. The higher-reaction rate of [Pt(en)(2)](2+) compared with [Pt(NH3)(4)](2+) is due to a higher electron density in the d(z)2 orbital making it more readily available to accommodate the Cl+ leaving from the platinum(IV). The redox rates depend strongly on the thermodynamic driving force, reflecting a significant weakening of the Cl-Pt-IV bonds in the transition states. The much faster reduction of [Pt(CN)(4)Cl-2](2-) compared with Pt(IV) ammine complexes previously studied is rationalized in terms of transition state stabilization due to the strong sigma-donor and pi-acceptor properties of cyanide. (C) 1998 Elsevier Science S.A. All rights reserved. (Less)
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- author
- Shi, Tiesheng LU and Elding, Lars Ivar LU
- organization
- publishing date
- 1998
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Inorganic chemistry, Platinum(II) complexes, Ammine complexes, Cyano complexes, Kinetics, Reaction mechanism
- in
- Inorganica Chimica Acta
- volume
- 1998
- issue
- 282
- pages
- 6 pages
- publisher
- Elsevier
- external identifiers
-
- scopus:0008683244
- ISSN
- 0020-1693
- DOI
- 10.1016/S0020-1693(98)00199-6
- language
- English
- LU publication?
- yes
- id
- 971dece4-36d6-45fd-85c5-3765ca763a39
- date added to LUP
- 2016-12-18 18:38:44
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- 2022-01-30 08:32:47
@article{971dece4-36d6-45fd-85c5-3765ca763a39,
abstract = {{Reduction of trans-[Pt(CN)(4)Cl-2](2-) by [Pt(NH3)(4)](2+) and [Pt(en)(2)](2+) was studied at 25 degrees C in the range 0 less than or equal to [Cl-] less than or equal to 0.4 M by use of stopped-flow spectrophotometry. The stoichiometry [Pt(IV)]:[Pt(II)] is 1:1. Rapid-scan spectra show clear-cut isosbestic points, indicating that no reaction intermediates are accumulated to a significant amount. For pseudo first-order conditions with excess Pt(II), the observed rate constants can be expressed as k(obsd)=(k(1)+k(2)K[Cl-])[Pt(II)], with k(1)=400+/-10 and (3.3+/-0.4)x10(3)M(-1)s(-1), and k(2)K= (3.25 +/-0.04) X 10(4) and (6.67 +/-0.07) x 10(5) M-2 s(-1) at 25 degrees C for reduction by [Pt(NH3)(4)](2+) and [Pt(en)(2)](2+), respectively. The mechanism involves two parallel reaction pathways. The analysis of the ionic strength dependence of k(1), together with the rapid-scan spectra, implies that reduction of trans-[Pt(CN)(4)Cl-2](2-) by these Pt(II) complexes takes place directly via chloride-bridged transition states of the type [H2O ... Pt-II... Cl ... Pt-IV... Cl](not equal) for the k(1) pathway, or [Cl ... Pt-II... Cl ... Pt-IV... Cl](not equal) for the k(2) path. The higher-reaction rate of [Pt(en)(2)](2+) compared with [Pt(NH3)(4)](2+) is due to a higher electron density in the d(z)2 orbital making it more readily available to accommodate the Cl+ leaving from the platinum(IV). The redox rates depend strongly on the thermodynamic driving force, reflecting a significant weakening of the Cl-Pt-IV bonds in the transition states. The much faster reduction of [Pt(CN)(4)Cl-2](2-) compared with Pt(IV) ammine complexes previously studied is rationalized in terms of transition state stabilization due to the strong sigma-donor and pi-acceptor properties of cyanide. (C) 1998 Elsevier Science S.A. All rights reserved.}},
author = {{Shi, Tiesheng and Elding, Lars Ivar}},
issn = {{0020-1693}},
keywords = {{Inorganic chemistry; Platinum(II) complexes; Ammine complexes; Cyano complexes; Kinetics; Reaction mechanism}},
language = {{eng}},
number = {{282}},
pages = {{55--60}},
publisher = {{Elsevier}},
series = {{Inorganica Chimica Acta}},
title = {{Kinetics and mechanism for reduction of trans-dichlorotetracyanoplatinate(IV) by tetraammineplatinum(II) and bis(ethylenediammine)platinum(II)}},
url = {{http://dx.doi.org/10.1016/S0020-1693(98)00199-6}},
doi = {{10.1016/S0020-1693(98)00199-6}},
volume = {{1998}},
year = {{1998}},
}