Bent Cyclopenta-2,4-dienylideneketene: Spectroscopic and ab initio Study of Reactive Intermediate

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Title:Bent Cyclopenta-2,4-dienylideneketene: Spectroscopic and ab initio Study of Reactive Intermediate
Creators:
Radziszewski, Juliusz G.
Kaszynski, Piotr
Friderichsen, Anders
Abildgaard, Jens
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 63, 8, pp. 1094-1106
Uncontrolled Keywords:<i>Ab initio</i> calculations, Benzyne, IR spectrum of cyclopenta-2,4-dienylideneketene, Photolysis of phthalic anhydride, Ketenes, Matrix isolation

Abstract

Results of an experimental and theoretical study of cyclopenta-2,4-dienylideneketene (<strong>3</strong>), a highly unstable reactive intermediate, are reported. The ketene was prepared, under matrix isolation conditions at 4.2 or 10 K, by laser photocarbonylation of 1,2-didehydrobenzene (<strong>1</strong>) photogenerated earlier from phthalic anhydride (<strong>2</strong>). FTIR polarization measurements performed on partially photooriented samples of <strong>3</strong> immobilized in solid neon or argon provide infrared transition moment directions for most of the observed vibrations. Experimental results confirm that the ketene is bent, as predicted by <i>ab initio </i>calculations. Utilizing two isotopically modified <strong>3</strong>, <strong>3b</strong> and <strong>3c</strong>, on the basis of the infrared absorption spectrum alone, we have analyzed and assigned its vibrations in a way, which leaves no doubt about the bent ketene structure. This work was motivated by a long standing confusion surrounding the assignments of the vibrations in 1,2-didehydrobenzene (<strong>1</strong>), especially of its "triple" bond stretch.

Title:Bent Cyclopenta-2,4-dienylideneketene: Spectroscopic and ab initio Study of Reactive Intermediate
Creators:
Radziszewski, Juliusz G.
Kaszynski, Piotr
Friderichsen, Anders
Abildgaard, Jens
Uncontrolled Keywords:<i>Ab initio</i> calculations, Benzyne, IR spectrum of cyclopenta-2,4-dienylideneketene, Photolysis of phthalic anhydride, Ketenes, Matrix isolation
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:63
Number:8
Page Range:pp. 1094-1106
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19981094UNSPECIFIED
ID Code:1368
Item Type:Article
Deposited On:06 Feb 2009 17:09
Last Modified:06 Feb 2009 16:09

Citation

Radziszewski, Juliusz G.; Kaszynski, Piotr; Friderichsen, Anders; Abildgaard, Jens (1998) Bent Cyclopenta-2,4-dienylideneketene: Spectroscopic and ab initio Study of Reactive Intermediate. Collection of Czechoslovak Chemical Communications, 63 (8). pp. 1094-1106. ISSN 0010-0765

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