Farbe und Konstitution bei Azoverbindungen

Abstract

Das faszinierende und rätselhafte Violett der neuen Azo‐bisphosphorsäure‐Derivate Y2OPNNPOY2 war Anlaß zur Darstellung und spektroskopischen Charakterisierung von mehr als 60 Azoverbindungen. Für die farbbedingenden langwelligen n → π*‐Übergänge ergaben sich dabei Gesetzmäßigkeiten, die zur Annahme substituentenspezifischer Absorptionsinkremente berechtigen. Orbital‐Modelle lassen den komplexen Zusammenhang zwischen Farbe und Konstitution bei Azoverbindungen qualitativ verstehen. IR‐ und UV‐Daten belegen eine Konjugationssperrwirkung durch Phosphor(+5) der Koordinationszahl vier. Die unerwartet langwellige Absorption des demnach nur aus vier Atomen bestehenden π‐Systems kann eine π*‐d‐Orbitalwechselwirkung erklären. Die beschriebenen Substituenteneffekte haben allgemeine Bedeutung: n→π*‐Übergänge anderer Chromophore werden in gleicher Weise beeinflußt.

Spectroscopic Properties of Organic Azo Compounds

“…Aromatic cis azo compounds cannot be planar because of the steric hindrance of the o-hydrogen atoms. cis-Azobenzene has a planar azo group, but the phenyl rings are parallel to each other and are twisted by 56" out of the plane of the azo group [71. The azo group in the cis configuration can also be part of an aliphatic or aromatic ring system, as in 2,3-diazabicyclo[2.2.1]-2-heptene ( 3 ) , the corresponding diazabicy-clooctene ( 4 ) , pyrazolines such as ( 5 ) , ( 6 ) , and ( 7 ) , or o-diazines such as pyridazine (8), phthalazine ( 9 ) , or benzo[c]cinnoline (10).…”

“…Properties of some onium carbonylmetalates[3] goes desilylation even on reaction with the phosphorussilyl ylides''].The structures of the products, which are pale yellow salts, sensitive to oxygen, can be proved by analysis and NMR and IR spectroscopy[51. Their behavior towards organometallic bases in transylidation and deprotonation processes [(a) and (b), respectively] is comparable with that of onium+ [ ( CH3),PI0[M(CO)3-n-C5H51@ M=Mo, WOf the onium salts studied so far, a few are extremely reactive.…”

Poly(arylazophosphonate)s: A New Polymer Class with Arylazophosphonate Units in the Main Chain

“…Some arylazophosphonate-containing compounds have been previously described but were unsatisfactorily characterized. [8][9][10][11][12] The structure of the polymers can be proved by comparison of the analytical data of the model compounds with the analytical data of the polymers.…”

“…The synthesis was carried out by N-P coupling of aromatic diazonium salts with diesters of the phosphoric acid (Scheme 1). 8,9 Arylazophosphonates (3) can be isolated as red oils or as crystalline solids and were synthesized in a great variety with several substituents R 1 , R 2 , and R 3 . 8,[10][11][12]…”

Azo Compounds

“…The coupling of aromatic diazonium salts with a variety of aromatic com pounds is the basis of the azo dye industry [2][3][4][5]. A variety of dying techniques are available but, fundamentally, two procedures are involved :…”