Rooney, A. Denise and McGarvey, John J. and Gordon, Keith C. and McNicholl, Ruth-Anne and Schubert, Ulrich and Hepp, Wolfgang
(1993)
Laser Photochemistry and Transient Raman Spectroscopy
of Silyl-Substituted Fischer-Type Carbene Complexes.
Organometallics, 12 (4).
pp. 1277-1282.
ISSN 0276-7333
Abstract
Pulsed laser irradiation of the silyl-substituted carbene complexes (CO)5W=C(XR)SiPh3
(XR = NC4H8 (1); = OEt (2)) in various solvents has been investigated using transient absorbance
and time-resolved resonance Raman scattering as monitoring techniques. Irradiation of (1) in
noncoordinating or weakly-coordinating solvents at 355 nm within the ligand field absorption
band results in the rapid formation, within the laser pulse duration, of a permanent photoproduct.
Saturation of the irradiated solution with CO results in regeneration of the starting complex
1. IR and Raman spectral data suggest that the photoproduct is the internally stabilized 16-
electron species (CO)4W=C(NC,iH8)SiPh3. The observations are discussed in relation to the
previously reported formation of the same 16-electron species by thermolysis of 1. When the
irradiation is carried out in CH3CN as solvent, UV-visible evidence suggests formation of the
photosubstituted species (CO)4(CH3CN) W=C(NC4Hg)SiPh3. No photoactivity, either transient
or permanent, is seen in any solvent when the irradiation is carried out at 416 nm, a wavelength
which falls within the MLCT absorption region of 1. When the ethoxy-substituted carbene
complex 2 is irradiated in either the LF or MLCT absorption regions a transient species forms
rapidly, within the laser pulse duration, and decays on a time scale of several μß, with a lifetime
dependent on solvent polarity but independent of CO concentration in solution. Time-resolved
resonance Raman studies in which the sample is photolyzed at 355 nm and probed by means
of a delayed pulse at 406 nm show the formation and decay of a transient consistent with the
flash photolysis results. The data are interpreted in terms of photoinduced anti-syn isomerization
of 2 about the Ccarbene~0 bond.
| Item Type: |
Article
|
| Additional Information: |
Cite as: Organometallics 1993, 12, 4, 1277–1282 |
| Keywords: |
Laser; Photochemistry; Transient; Raman; Spectroscopy;
Silyl-Substituted; Fischer-Type; Carbene; Complexes; |
| Academic Unit: |
Faculty of Science and Engineering > Chemistry |
| Item ID: |
14526 |
| Identification Number: |
https://doi.org/10.1021/om00028a050 |
| Depositing User: |
Dr. Denise Rooney
|
| Date Deposited: |
09 Jun 2021 15:24 |
| Journal or Publication Title: |
Organometallics |
| Publisher: |
American Chemical Society |
| Refereed: |
Yes |
| URI: |
|
| Use Licence: |
This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available
here |
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