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Valence Isomerism in Selected Heterocyclic Systems
Author(s) -
Paquette Leo A.
Publication year - 1971
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.197100111
Subject(s) - valence (chemistry) , isomerization , tautomer , chemistry , degenerate energy levels , bicyclic molecule , stereochemistry , computational chemistry , physics , catalysis , quantum mechanics , organic chemistry
Valence isomerization and the phenomenologically related principle of valence tautomerism, as they apply to several nitrogen‐containing heterocyclic systems, are discussed herein. Attention is called first to 1H‐azepines and the reluctance of such substances to isomerize to azanorcaradienes. The role of homo‐1H‐azepines in this context is then briefly outlined. Azocines (azacyclooctatetraenes) are seen to occupy an interesting position in the sense that pronounced shifts in the position of equilibrium (from almost entirely monocyclic to virtually completely bicyclic) occur with substitutional alterations of various types. The capability of azabullvalenes for degenerate valence isomerization is the next presented, and contrast is made with the properties of benzazabullvalenes and an azasemibullvalene derivative.