Über zweistufige Redoxsysteme, IX¹⁾ Polarographie²⁾ und Spektroskopie heterocyclisch substituierter Äthylene und ihrer höheren Oxidationsstufen

Abstract

Die Systeme 1 und 2 sowie 2B bis 4B zeigen zweistufige Polarogramme, aus denen sich Semichinonbildungskonstanten K = 102-1014 ableiten lassen. Der Einflul3 der Struktur auf K sowie die Lage von El und E2 werden diskutiert. Nur fur 2 und 2B sind Elektronenspektren der Stufen Red, Sem und Ox zu erhalten. Two-step Redox Systems, IX1). -Polarography and Spectroscopy of Heterocyclic Substituted Ethylenes and Their Higher Oxidation LevelsThe systems 1, 2, 2B to 4B display two-step polarograms from which semiquinone formation constants K = 102-1014 can be derived. The dependence on structure of K, El and Ez are discussed. Absorption spectra for Red, Sem, and Ox could only be obtained for 2 and 2B. ZielsetzungIn der voranstehenden Mitteilung 1) wurde die Synthese der 2.2'-verkniipften Heterocyclen 1 -3 beschrieben. Zum Vergleich wurden auI3erdem die analogen Verbindungen 2B und 3B aufgebaut, in denen beide Molekiilhalften durch die Alkyl-Brucke in eine coplanare Form gezwungen werden. Von besonderem Interesse ist schliei3lich das Verhalten von 3B und 4B, in denen zwei nahe verwandte, isomere Formen eines heterocyclischen x-Systems vorliegen. Wie man sieht, stehen fur die Systeme 2, 3 und 2B die sich um zwei Elektronen unterscheidenden Oxidationsstufen Red und Ox zur Verfugung.

Electron Transfer to Benzenes by Photoactivated Neutral Organic Electron Donor Molecules

“…Our recent research has probed the ground‐state donor properties of highly reactive neutral organic reducing agents. Thus, we have shown that the neutral ground‐state organic electron donor 1 7, 8 (Scheme ) reduces iodoarenes9, 10 to aryl radicals11 while the stronger donors 2 12 and 3 13 under milder conditions, afford aryl anions from the same substrates through transfer of two electrons. These donors also reduce sulfonamides, acyloin derivatives, and Weinreb amides 13…”

Hybrid super electron donors – preparation and reactivity

“…Whereas tetrathiafulvalenes and analogues [ 1 – 5 ] have principally found widespread applications in materials science, tetraazaalkenes and related compounds are much more reactive and are of potential or actual interest as reagents in synthesis [ 6 – 33 ]. Among the tetraazaalkenes, those that are converted to aromatic molecules upon oxidation, e.g., tetraazafulvalenes 1 and 2 , are extremely reactive, and their electrochemical properties have been studied in some depth [ 13 – 16 ].…”

Electron Transfer to Benzenes by Photoactivated Neutral Organic Electron Donor Molecules

“…Thus, we have shown that the neutral ground-state organic electron donor 1 [7,8] (Scheme 1) reduces iodoarenes [9,10] to aryl radicals [11] while the stronger donors 2 [12] and 3 [13] under milder conditions, afford aryl anions from the same substrates through transfer of two electrons. These donors also reduce sulfonamides, acyloin derivatives, and Weinreb amides.…”

“…Thus, we have shown that the neutral ground-state organic electron donor 1 [7,8] (Scheme 1) reduces iodoarenes [9,10] to aryl radicals [11] while the stronger donors 2…”