Issue 12, 2004
From the journal:

New Journal of Chemistry

W(CO)5-pyridine π-acceptor complexes: theoretical calculations and a laser photolysis study

Janusz Zakrzewski,*a   Jacques A. Delaire,b   Chantal Danielc  and  Isabelle Cote-Bruandc  

* Corresponding authors

a Department of Organic Chemistry, University of Łódź, Narutowicza 68, Łódź, Poland
E-mail: janzak@uni.lodz.pl
Fax: (+42) 678 65 83
Tel: (+42) 678 47 50

b Laboratoire de Photophysique et Photochimie Supramoléculaires et Macromoléculaires (CNRS UMR 8531), Ecole Normale Supérieure de Cachan, Cachan cédex, France
E-mail: jdelaire@ppsm.ens-cachan.fr
Fax: (+33) 1 47 40 24 54
Tel: (+33) 1 47 40 53 37

c Laboratoire de Chimie Quantique (CNRS UMR 7551), Université Louis Pasteur, Institut Le Bel, 4, rue Blaise Pascal, Strasbourg, France
E-mail: daniel@quantix.u-strasbg.fr
Fax: (+33) 3 90 24 15 89
Tel: (+33) 3 90 24 13 02

Abstract

Theoretical (time-dependent DFT and MS-CASPT2) calculations showed that the two lowest-energy excited states of W(CO)5 complexes of 4-[(E)-2-carbomethoxy-2-cyanovinyl)]pyridine, 1 and 4-(2,2-dicyanovinyl)pyridine, 2 have metal-to-ligand charge transfer (MLCT) character. They result from an electron transfer from a tungsten-centered orbital (5dx2 − y2 or 5dxy) to the π* orbital localized on the ethylenic bridge. The calculated lowest excitation energy for 1 (537 nm) is close to the experimental value of 522 nm in cyclohexane. Laser flash photolysis at 532 nm in the nanosecond and picosecond domains showed that for both complexes transient excited states are formed with a quantum yield close to 1. Their lifetimes are about 10 times shorter than those observed previously for similar W(CO)5-pyridine complexes, with the lifetime of the excited state of compound 1 being longer than that of compound 2. Increasing the solvent polarity decreases the lifetimes in both cases. Complexes 1 and 2 are nonfluorescent, photostable, and do not undergo photosolvation.

Graphical abstract: W(CO)5-pyridine π-acceptor complexes: theoretical calculations and a laser photolysis study

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Article information

DOI
https://doi.org/10.1039/B408617A
Article type
Paper
Submitted
07 Jun 2004
Accepted
03 Sep 2004
First published
15 Nov 2004

New J. Chem., 2004,28, 1514-1519

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W(CO)5-pyridine π-acceptor complexes: theoretical calculations and a laser photolysis study

J. Zakrzewski, J. A. Delaire, C. Daniel and I. Cote-Bruand, New J. Chem., 2004, 28, 1514 DOI: 10.1039/B408617A

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