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Adducts of macrocyclic polyethers (crown ethers) and aminopolyethers1,2 having hydrogen bonds with polar organic molecules, especially with CH-acidic compounds, are described. These can be isolated as solids, and are, as a rule, stoichiometrically consistent. The chemical shift of the 1H NMR signals of the adducts of malononitrile with various crown ethers corresponds to the anionic reactivity of potassium complexes of the crown ethers in the course of nucleophilic substitution reactions.

Die Struktur des Adduktes 2 Malononitril · 18‐Krone‐6 wurde röntgenographisch bestimmt und bis zu einem R‐Faktor von 0.049 verfeinert. Die Verbindung kristallisiert in der Raumgruppe P21/c. Die Malononitrilmoleküle bilden über CH · · · ·O‐Wasserstoffbrücken mit dem Kronenether analog den bicyclischen Aminopolyethern einen dreidimensionalen Hohlraum von ca. 100 pm Durchmesser. Der Kronenether hat wie im KSCN‐Komplex annähernd D3d‐Symmetrie.

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.

In the 1 : 2 host-guest complex formed between 1,4,7,10,13,16-hexaoxacyclo-octadecane (18-crown-6) and benzenesulphonamide, the crown ether adopts nearly the same conformation as the uncomplexed hexaether ; the complex is held together mainly by N-H ---0 hydrogen bonds.THE ability of crown ethers to form host-guest complexes with alkaline earth metal cations and ammonium salts is well known. Preliminary X-ray crystallographic results of Dunitz et aZ.3 shows that 18-crown-6 exists in different W . Germany) conformations in free and complexed forms. X-Ray crystal structure determinations of complexes of crown ethers with CH-4 and OH-acid5 substrates show that the crown ether in these compounds adopts a conformation with D,,-symmetry which is typical of potassium complexes.We report the solid-state structure of the product of reaction of 18-crown-6 with the NH-acid substrate, benzenesulphonamide, which can be obtained by a method similar to that used earlier for other compounds.6 Crystals of the complex are obtained as colourless needles, m.p. 365 K, which gave satisfactory microanalytical data.

Attempts to explain the surprising violet color of the new azobisphosphonic acid derivatives Y2OPNNPOY2 have led to the preparation and spectroscopic characterization of more than 60 azo compounds. The long‐wavelength n → π* transitions on which the color depends exhibit regularities which justify the assumption of substitutent‐specific absorption increments. The complex relation between color and constitution of azo compounds can be qualitatively explained with the aid of orbital models. Infrared and ultraviolet spectral data show that conjugation is inhibited by tetra‐coordinated phosphorus (V). the π‐system of these compounds therfore comprises only for atoms, P·N·N·P. The unexpected violet color of the phosphorus azo compounds can be ascribed to a π*/d orbital interaction. The substituent effects described have general significance, and n→π*transitions of other chromophores are similarly affected.

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