6308-52-7Relevant articles and documents
Nitrile imines: Matrix isolation, IR spectra, structures, and rearrangement to carbodiimides
Begue, Didier,Qiao, Greg Guanghua,Wentrup, Curt
scheme or table, p. 5339 - 5350 (2012/05/20)
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-SiMe323, Ph-CNN-Ph 29, Ph3C-CNN-CPh334, 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 PhCNNSiMe323, 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, PhCNNCH317, and Ph3C-CNN-CPh334). 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.
