Sydnone photochemistry: Direct observation of earl's bicyclic lactone valence isomers (oxadiazabicyclo[2.1.0] pentanones), formation of carbodiimides, reaction mechanism, and photochromism

Veedu, Rakesh N., Kvaskoff, David and Wentrup, Curt (2014). Sydnone photochemistry: Direct observation of earl's bicyclic lactone valence isomers (oxadiazabicyclo[2.1.0] pentanones), formation of carbodiimides, reaction mechanism, and photochromism. In: Special Issue : Presents a collection of papers authored by delegates at the meeting. 6th Heron Island Conference on Reactive Intermediates and Unusual Molecules, Heron Island, Qld, Australia, (457-468). 7 - 13 July 2013. doi:10.1071/CH13536


Author Veedu, Rakesh N.
Kvaskoff, David
Wentrup, Curt
Title of paper Sydnone photochemistry: Direct observation of earl's bicyclic lactone valence isomers (oxadiazabicyclo[2.1.0] pentanones), formation of carbodiimides, reaction mechanism, and photochromism
Conference name 6th Heron Island Conference on Reactive Intermediates and Unusual Molecules
Conference location Heron Island, Qld, Australia
Conference dates 7 - 13 July 2013
Proceedings title Special Issue : Presents a collection of papers authored by delegates at the meeting   Check publisher's open access policy
Journal name Australian Journal of Chemistry   Check publisher's open access policy
Place of Publication Collingwood, VIC Australia
Publisher CSIRO
Publication Year 2014
Year available 2013
Sub-type Fully published paper
DOI 10.1071/CH13536
ISSN 0004-9425
1445-0038
Volume 67
Issue 3
Start page 457
End page 468
Total pages 12
Language eng
Abstract/Summary The matrix photolyses of 3-phenyl-, 3-pyridyl, and 3,4-diphenylsydnones 16, 19, and 22 were investigated by matrixisolation infrared spectroscopy. The formation of the neutral, bicyclic lactone valence isomers postulated by Earl - the oxadiazabicyclo[2.1.0]pentanones exo-17 and exo-20 - was clearly observed in the first two cases and is also likely in the case of exo-23 (C=Oabsorptions in the IR at 1881, 1886, and 1874 cm -1, respectively). The efficient photodecomposition of sydnones to carbodiimides RN=C=NR0 (18, 21, and 24) and CO2 was established in all three cases. The formation of benzonitrile 27 and azacycloheptatetraene 29 in the matrix photolysis of diphenylsydnone 22 is indicative of diphenylnitrile imine PhCNNPh 26 as an intermediate (2340 cm -11). Neither bicyclic lactones nor carbodiimides have been observed previously in sydnone photochemistry. A general reaction mechanism for the formation of carbodiimides, nitrile imines, and photochromism is put forward.
Subjects 1600 Chemistry
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Conference Paper
Collections: Official 2015 Collection
School of Chemistry and Molecular Biosciences
 
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