Nitrile Imines: Matrix Isolation, IR Spectra, Structures, and Rearrangement to Carbodiimides

Bégué, Didier, Qiao, Greg GuangHua and Wentrup, Curt (2012) Nitrile Imines: Matrix Isolation, IR Spectra, Structures, and Rearrangement to Carbodiimides. Journal of the American Chemical Society, 134 11: 5339-5350. doi:10.1021/ja2118442

Author Bégué, Didier
Qiao, Greg GuangHua
Wentrup, Curt
Title Nitrile Imines: Matrix Isolation, IR Spectra, Structures, and Rearrangement to Carbodiimides
Journal name Journal of the American Chemical Society   Check publisher's open access policy
ISSN 0002-7863
Publication date 2012-03-21
Sub-type Article (original research)
DOI 10.1021/ja2118442
Volume 134
Issue 11
Start page 5339
End page 5350
Total pages 12
Place of publication Washington, DC, United States
Publisher American Chemical Society
Collection year 2013
Language eng
Formatted abstract
The structures and reactivities of nitrile imines are subjects of continuing debate. Several nitrile imines were generated photochemically or thermally and investigated by IR spectroscopy in Ar matrices at cryogenic temperatures (Ph-CNN-H 6, Ph-CNN-CH317, Ph-CNN-SiMe3 23, Ph-CNN-Ph 29, Ph3C-CNN-CPh3 34, and the boryl-CNN-boryl derivative 39). The effect of substituents on the structures and IR absorptions of nitrile imines was investigated computationally at the B3LYP/6-31G* level. IR spectra were analyzed in terms of calculated anharmonic vibrational spectra and were generally in very good agreement with the calculated spectra. Infrared spectra were found to reflect the structures of nitrile imines accurately. Nitrile imines with IR absorptions above 2200 cm–1 have essentially propargylic structures, possessing a CN triple bond (typically PhCNNSiMe3 23, PhCNNPh 29, and boryl-CNN-boryl 39). Nitrile imines with IR absorptions below ca. 2200 cm–1 are more likely to be allenic (e.g., HCNNH 1, PhCNNH 6, HCNNPh 43, PhCNNCH3 17, and Ph3C-CNN-CPh3 34). All nitrile imines isomerize to the corresponding carbodiimides both thermally and photochemically. Monosubstituted carbodiimides isomerize thermally to the corresponding cyanamides (e.g., Ph-N═C═N-H 5 → Ph-NH-CN 8), which are therefore the thermal end products for nitrile imines of the types RCNNH and HCNNR. This tautomerization is reversible under flash vacuum thermolysis conditions.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Chemistry and Molecular Biosciences
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Created: Fri, 11 May 2012, 09:28:11 EST by Lucy O'Brien on behalf of School of Chemistry & Molecular Biosciences