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Multistep Reversible Redox Systems, XLVII 1) N,N ′‐Dicyanoquinonediimines – A New Class of Compounds, II: Comparison of Redox Properties with those of Quinones and Tetracyanoquinodimethanes
Author(s) -
Aumüller Alexander,
Hünig Siegfried
Publication year - 1986
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.198619860115
Subject(s) - chemistry , redox , planarity testing , substituent , chemical stability , group (periodic table) , stereochemistry , medicinal chemistry , crystallography , computational chemistry , inorganic chemistry , organic chemistry
By determining the E 2 (and in part E 1 ) redox potentials of the quinoid compounds 1 – 9 , the close chemical similarity of the groups C = X [X O, NCN, C(CN) 2 ] has been quantitatively confirmed. Especially the dicyanodiimines 2 and 5 are very similar to TCNQ derivatives 3 . Substituent effects on the potentials E 2 are linear with (σ m + σ p )/2 Hammett constants. Most deviations from the expected thermodynamic stability of the radical anions ( K SEM ) are due to lack of planarity especially with systems containing the Y‐shaped rigid =C(CN) 2 group.