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Reactivity of Carbenes and Related Compounds towards Molecular Nitrogen
Author(s) -
Grieve Duncan M. A.,
Lewis Graham E.,
Ravenscroft Michael D.,
Skrabal Peter,
Sonoda Takaaki,
Szele Ivanka,
Zollinger Heinrich
Publication year - 1985
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19850680534
Subject(s) - chemistry , diazo , carbene , electrophile , reactivity (psychology) , singlet state , medicinal chemistry , imidazole , cyclopentadiene , photochemistry , stereochemistry , organic chemistry , catalysis , medicine , physics , alternative medicine , pathology , nuclear physics , excited state
The thermal N 2 exchange of a number of 15 N‐labelled diazo compounds was studied in solution. The compounds involved were 3‐diazo‐1‐methylindolin‐2‐one ( 1 ), 9‐diazofluorene ( 2 ), 5‐diazo‐1,3‐cyclopentadiene‐1,2,3,4‐tetracarbonitrile ( 3 ), 2‐diazo‐2 H ‐imidazole‐4,5‐dicarbonitrile ( 4 ), 4‐diazocyclohexa‐2,5‐dienone ( 5 ), and the conjugate acids of 4 and 5 , namely 4,5‐dicyano‐1 H ‐imidazole‐2‐diazonium ion ( 6 ) and 4‐hydroxybenzenediazonium ion ( 7 ). Only 1 , 4 , 6 , and 7 exchange their diazo group with ‘external’ molecular N 2 . The results are explained on the hypothesis that only organic species which have an empty σ orbital and which are effective in π electron back‐donation are able to react with N 2 . Thus, reaction with carbenes is likely to occur only if the carbene is in the 1 A 2 singlet state and if its electrophilicity is high.