Heterocyclic Substituted Arenediazonium Salts with a Long‐wave‐length Range of Sensitivity. II. 4‐(1‐Heterocycliden‐2,3‐diaza‐prop‐2‐en‐3‐yl)‐arenediazonium tetrafluoroborates The title compounds (3) are obtained by reaction of aromatic bis‐diazonium salts with substituted 2‐benzylidene‐1,3‐dithioles and 2‐benzylidene‐1,3‐diselenole, respectively. The maximum of the long wave‐length absorption band of 3 varies from 580 nm up to 665 nm depending on the structure of the compound. The quantum yields of the photolysis of the diazonium salts 3 are low (1 · 10−4 to 7 · 10−3). The azo dyes obtained from 3 with usual azo‐couplers absorb in a shorter wave‐length range than the corresponding diazonium salts themselves (hypso‐coupling effect).

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m), 7,G5 (m) 8,01 (m, Phcnyl-H) ppm; Signale des (E)-Isomeren. (E)-2a [mit L'Sq/, (Z)-isomer]: dunkelbraune Blattchen; Schmp. 170-172°C und 183-184°C; UVjVIS (MeCN): 221,5 (4,4G), 291,S (4,42)), 450 (3,37) nm (lge); IH-NMR (CDCI,): 2,39 (9, CH,); 7,06 (s, H5); 7,28 (pd), 7,86 (pd, Tolyl-H); 7,6 (m), 7,92 (m, Phenyl-H); 9,18 (8, breit, N-H)ppm; Signale des (Z)-Isomeren. -2b: aus l b , X = ClO,, analog Vorschrift fur 2a. Schwarze Rhomben (MeCN); Ausbeute 70%; Schmp. 195°C; C2,HI9N3O2S3 (465,G); UVjVIS (MeCIS): 288(4,31), 458 (3,97)nm (IgE); lH-NMR (CDCI,): 2,30 (s, CH,); 6,GO (s, H5); 7,16 (m, 3H), 7,41 (m, 7H), 7,70 (m, 4H, aromat. H); 9,15 (s,N-H) ppm. -2c: Man tropft zur Losung von 3 mmol I c , X = BF,, in 10 ml McCN bei Raumtemperatur untcr Ruhren 3mmol NEt, in 5 m l MeCN, worauf sich aus dcr dunkelroten Losung das Produkt abscheidet (Isolierung von etwa 100 mg cines undefinierten Produktes ails der