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Application of stopped flow techniques and energy dispersive EXAFS for investigation of the reactions of transition metal complexes in solution: activation of nickel ?-diketonates to form homogeneous catalysts, electron transfer reactions involving iron(III) and oxidative addition to iridium(I)

Application of stopped flow techniques and energy dispersive EXAFS for investigation of the reactions of transition metal complexes in solution: activation of nickel ?-diketonates to form homogeneous catalysts, electron transfer reactions involving iron(III) and oxidative addition to iridium(I)
Application of stopped flow techniques and energy dispersive EXAFS for investigation of the reactions of transition metal complexes in solution: activation of nickel ?-diketonates to form homogeneous catalysts, electron transfer reactions involving iron(III) and oxidative addition to iridium(I)
Stopped-flow techniques of rapid mixing have been combined with energy dispersive X-ray absorption spectroscopy to monitor the reaction of Ni(dpm)(2) {dpm = (BuC)-C-t(O)CHC(O)Bu-t} by aluminium alkyls (AlEt2X, X = OEt and Et) to form the active species for the catalytic di- and tri-merisation of hex-1-ene. Acquisition times down to ca. 30 ms were achieved on Station 9.3 of the SRS using a photodiode array detector. The EXAFS features of the resulting solution complexes are of the form [Ni(O-O)(R) (alkene)]. In the presence of PPh3, [Ni(O-O)(R)(PPh3)] appears to be the predominant type of species. The reduction of aqueous Fe(III) by hydroquinone was investigated on ID24 at the ESRF by Fe K-edge energy dispersive EXAFS with a CCD camera as detector; spectra were obtained in 1 ms or longer. No intermediate inner sphere complex was detected prior to the formation of aqueous Fe(II). Finally the oxidative addition of CH3SO3CF3 to [IrI2(CO)(2)](-) was monitored on Station 9.3 with a silicon microstrip detector. A single acquisition of 400 mus was feasible, with spectra recorded in multiples of 1.2 ms. In that time, the first stage of the reaction had been completed, with a slower stage thereafter. The results are consistent with the two-stage ionic oxidative addition mechanism.
alkene oligomerization catalyst, ray-absorption-spectroscopy, synchrotron radiation, carbonylation, spectrometer, timescale, methanol, systems
0301-7249
211-222
B. Abdul Rahman, M. Basyaruddin
f358d5b6-c450-4ea7-8a23-a609b20f152d
Bolton, Peter R.
a3c7a60c-0c36-4de4-b25b-5fc7e3c6b26f
Evans, John
05890433-0155-49fe-a65d-38c90ea25c69
Dent, Andrew J.
24c2a218-cb0e-4193-af0b-3ff1dc42b552
Harvey, Ian
c7d85326-0c7a-47b5-a50b-fd6bfebbe3cd
Diaz-Moreno, Sofia
4e280df3-7f62-4280-8058-2803c740ae00
B. Abdul Rahman, M. Basyaruddin
f358d5b6-c450-4ea7-8a23-a609b20f152d
Bolton, Peter R.
a3c7a60c-0c36-4de4-b25b-5fc7e3c6b26f
Evans, John
05890433-0155-49fe-a65d-38c90ea25c69
Dent, Andrew J.
24c2a218-cb0e-4193-af0b-3ff1dc42b552
Harvey, Ian
c7d85326-0c7a-47b5-a50b-fd6bfebbe3cd
Diaz-Moreno, Sofia
4e280df3-7f62-4280-8058-2803c740ae00

B. Abdul Rahman, M. Basyaruddin, Bolton, Peter R., Evans, John, Dent, Andrew J., Harvey, Ian and Diaz-Moreno, Sofia (2003) Application of stopped flow techniques and energy dispersive EXAFS for investigation of the reactions of transition metal complexes in solution: activation of nickel ?-diketonates to form homogeneous catalysts, electron transfer reactions involving iron(III) and oxidative addition to iridium(I). Faraday Discussions, 122, 211-222. (doi:10.1039/b202833f).

Record type: Article

Abstract

Stopped-flow techniques of rapid mixing have been combined with energy dispersive X-ray absorption spectroscopy to monitor the reaction of Ni(dpm)(2) {dpm = (BuC)-C-t(O)CHC(O)Bu-t} by aluminium alkyls (AlEt2X, X = OEt and Et) to form the active species for the catalytic di- and tri-merisation of hex-1-ene. Acquisition times down to ca. 30 ms were achieved on Station 9.3 of the SRS using a photodiode array detector. The EXAFS features of the resulting solution complexes are of the form [Ni(O-O)(R) (alkene)]. In the presence of PPh3, [Ni(O-O)(R)(PPh3)] appears to be the predominant type of species. The reduction of aqueous Fe(III) by hydroquinone was investigated on ID24 at the ESRF by Fe K-edge energy dispersive EXAFS with a CCD camera as detector; spectra were obtained in 1 ms or longer. No intermediate inner sphere complex was detected prior to the formation of aqueous Fe(II). Finally the oxidative addition of CH3SO3CF3 to [IrI2(CO)(2)](-) was monitored on Station 9.3 with a silicon microstrip detector. A single acquisition of 400 mus was feasible, with spectra recorded in multiples of 1.2 ms. In that time, the first stage of the reaction had been completed, with a slower stage thereafter. The results are consistent with the two-stage ionic oxidative addition mechanism.

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More information

Published date: 2003
Keywords: alkene oligomerization catalyst, ray-absorption-spectroscopy, synchrotron radiation, carbonylation, spectrometer, timescale, methanol, systems

Identifiers

Local EPrints ID: 20070
URI: http://eprints.soton.ac.uk/id/eprint/20070
ISSN: 0301-7249
PURE UUID: 75ff2c99-7d5f-4f59-9707-7474d739a8af

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Date deposited: 24 Feb 2006
Last modified: 09 Jan 2022 06:04

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Contributors

Author: M. Basyaruddin B. Abdul Rahman
Author: Peter R. Bolton
Author: John Evans
Author: Andrew J. Dent
Author: Ian Harvey
Author: Sofia Diaz-Moreno

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