Bridge-splitting Kinetics, Equilibria and Structures of trans-bis-cyclooctene Complexes of Platinum(II)
(2003) In Dalton Transactions p.2519-2525- Abstract
- Cyclooctene (C8H14, cot) complexes of platinum(II) have been synthesised and characterised by means of multinuclear NMR, UV-Vis spectroscopy and X-ray crystallography. The bridge-splitting equilibrium constants of the dinuclear, chloride-bridged trans-[PtCl2(cot)]2, 1, in dichloromethane solvent at 298 K with MeOH, MeCN and cot, yielding trans-[PtCl2(cot)(MeOH)], 2, trans-[PtCl2(cot)(MeCN)], 3, and trans-[PtCl2(cot)2], 4, were determined by UV-Vis measurements as K12= 0.0169 ± 0.0015, K13= 9.7 ± 0.9 and K14= 2.05 ± 0.06 mol–1 dm3, respectively. Substitution of one cyclooctene from 4 by MeOH gives K42= 0.110 ± 0.009 and by MeCN K43= 2.25 ± 0.03. The bis-cyclooctene complexes 1 and 4 react quantitatively with chloride to give [PtCl3(cot)]–,... (More)
- Cyclooctene (C8H14, cot) complexes of platinum(II) have been synthesised and characterised by means of multinuclear NMR, UV-Vis spectroscopy and X-ray crystallography. The bridge-splitting equilibrium constants of the dinuclear, chloride-bridged trans-[PtCl2(cot)]2, 1, in dichloromethane solvent at 298 K with MeOH, MeCN and cot, yielding trans-[PtCl2(cot)(MeOH)], 2, trans-[PtCl2(cot)(MeCN)], 3, and trans-[PtCl2(cot)2], 4, were determined by UV-Vis measurements as K12= 0.0169 ± 0.0015, K13= 9.7 ± 0.9 and K14= 2.05 ± 0.06 mol–1 dm3, respectively. Substitution of one cyclooctene from 4 by MeOH gives K42= 0.110 ± 0.009 and by MeCN K43= 2.25 ± 0.03. The bis-cyclooctene complexes 1 and 4 react quantitatively with chloride to give [PtCl3(cot)]–, 5. The kinetics for bridge-splitting of 1 with MeOH, MeCN and cot was studied by conventional and cryo-stopped-flow spectroscopy. Second-order rate constants at 298 K are 0.128 ± 0.003, 4.93 ± 0.02 and 0.0637 ± 0.0009 mol–1 dm3 s–1, respectively. The corresponding activation parameters are H= 43.7 ± 1.8, 42.0 ± 0.8 and 39.6 ± 0.9 kJ mol–1 and S=–115 ± 6, –91 ± 3 and –135 ± 3 J K–1 mol–1, indicating associative activation with a relatively large -TS contribution to G. Crystal and molecular structures of 1, 4, and the tetraphenylphosphonium salt of 5 have been determined, indicating a moderate ground-state trans influence of cyclooctene. The molecular structure of 4 with two CC double bonds coordinated trans to each other and perpendicular to the platinum coordination plane, features a significant Pt–C bond lengthening compared to cyclooctene complexes with chloride or nitrogen trans to cyclooctene, leading to high reactivity and thermodynamic instability. Equilibrium data confirm that the thermodynamic stability of a cyclooctene coordinated trans to another cyclooctene is much lower than trans to a ligand with less -back-bonding capacity. (Less)
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https://lup.lub.lu.se/record/128375
- author
- Otto, Stefanus ; Roodt, Andreas and Elding, Lars Ivar LU
- organization
- publishing date
- 2003
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Kinetics, Bridge splitting, Bis cyclooctene complexes, Plarinum
- in
- Dalton Transactions
- issue
- 12
- pages
- 2519 - 2525
- publisher
- Royal Society of Chemistry
- external identifiers
-
- wos:000183430100023
- scopus:9644291944
- ISSN
- 1477-9234
- DOI
- 10.1039/b302482m
- language
- English
- LU publication?
- yes
- additional info
- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Inorganic chemistry (ceased) (LUR000010)
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- cf1b6edb-0bf2-4fde-89e3-4880d738d3dd (old id 128375)
- date added to LUP
- 2016-04-01 11:38:17
- date last changed
- 2022-01-26 07:59:57
@article{cf1b6edb-0bf2-4fde-89e3-4880d738d3dd,
abstract = {{Cyclooctene (C8H14, cot) complexes of platinum(II) have been synthesised and characterised by means of multinuclear NMR, UV-Vis spectroscopy and X-ray crystallography. The bridge-splitting equilibrium constants of the dinuclear, chloride-bridged trans-[PtCl2(cot)]2, 1, in dichloromethane solvent at 298 K with MeOH, MeCN and cot, yielding trans-[PtCl2(cot)(MeOH)], 2, trans-[PtCl2(cot)(MeCN)], 3, and trans-[PtCl2(cot)2], 4, were determined by UV-Vis measurements as K12= 0.0169 ± 0.0015, K13= 9.7 ± 0.9 and K14= 2.05 ± 0.06 mol–1 dm3, respectively. Substitution of one cyclooctene from 4 by MeOH gives K42= 0.110 ± 0.009 and by MeCN K43= 2.25 ± 0.03. The bis-cyclooctene complexes 1 and 4 react quantitatively with chloride to give [PtCl3(cot)]–, 5. The kinetics for bridge-splitting of 1 with MeOH, MeCN and cot was studied by conventional and cryo-stopped-flow spectroscopy. Second-order rate constants at 298 K are 0.128 ± 0.003, 4.93 ± 0.02 and 0.0637 ± 0.0009 mol–1 dm3 s–1, respectively. The corresponding activation parameters are H= 43.7 ± 1.8, 42.0 ± 0.8 and 39.6 ± 0.9 kJ mol–1 and S=–115 ± 6, –91 ± 3 and –135 ± 3 J K–1 mol–1, indicating associative activation with a relatively large -TS contribution to G. Crystal and molecular structures of 1, 4, and the tetraphenylphosphonium salt of 5 have been determined, indicating a moderate ground-state trans influence of cyclooctene. The molecular structure of 4 with two CC double bonds coordinated trans to each other and perpendicular to the platinum coordination plane, features a significant Pt–C bond lengthening compared to cyclooctene complexes with chloride or nitrogen trans to cyclooctene, leading to high reactivity and thermodynamic instability. Equilibrium data confirm that the thermodynamic stability of a cyclooctene coordinated trans to another cyclooctene is much lower than trans to a ligand with less -back-bonding capacity.}},
author = {{Otto, Stefanus and Roodt, Andreas and Elding, Lars Ivar}},
issn = {{1477-9234}},
keywords = {{Kinetics, Bridge splitting; Bis cyclooctene complexes, Plarinum}},
language = {{eng}},
number = {{12}},
pages = {{2519--2525}},
publisher = {{Royal Society of Chemistry}},
series = {{Dalton Transactions}},
title = {{Bridge-splitting Kinetics, Equilibria and Structures of trans-bis-cyclooctene Complexes of Platinum(II)}},
url = {{http://dx.doi.org/10.1039/b302482m}},
doi = {{10.1039/b302482m}},
year = {{2003}},
}