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Novel Heterocumulenes: Bisiminopropadienes and Linear Ketenimines
Author(s) -
Wolf Reinhard,
Stadtmüller Stefan,
Wong Ming Wah,
Wentrup Curt,
BarbieuxFlammang Monique,
Flammang Robert
Publication year - 1996
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19960021020
Subject(s) - chemistry , matrix isolation , infrared spectroscopy , isotopomers , thermal decomposition , crystallography , spectroscopy , decomposition , stereochemistry , molecule , organic chemistry , physics , quantum mechanics
Flash vacuum thermolysis (FVT) of suitably substituted isoxazol‐5(4 H )‐ones 7–9 leads to three different types of ketenimines, namely, the isoxazolonoketenimines 2 , the novel bisiminopropadienes RNCCCNR ( 5 ), and the C ‐cyanoketenimines 14 , all characterized by a combination of FVT/matrix isolation/IR spectroscopy and FVT/MS. An unusual, linear CCN‐C backbone in ketenimines 2g and 2h is revealed by their exceptional spectroscopic properties as well as an X‐ray crystal structure of 2g , and confirmed by density functional calculations (B3LYP/6–31 G * ); these compounds are best described as resonance hybrids of ketenimines and isonitrile ylides R 2 C‐CN‐R'. The identification of the highly reactive bisiminopropadienes 5 is supported by the observed shifts in the IR bands of the 15 N and 13 C isotopomers as well as theoretical calculations, tert ‐Butyl‐substituted isoxazolones 7e and 7f , and 8i form the expected ketenimines 2 , which then undergo elimination of isobutene and CO 2 to generate C ‐cyanoketenimines 14 and 14i . N ‐Phenyl‐dicyanoketenimine 32 is also described.