1.2.4.5- Tetracyanopyrazine

X-ray structural information on halide binding to neutral organic it-receptors is limited to a few recent reports [23,24,62,89-91 ]2. In fact, the slow diffusion of hexane into a dichloromethane solutions of tetracyanopyrazine containing the alkylammonium salts of either chloride, bromide or iodide affords yellow to red crystals with UV-Vis absorptions closely resembling the elec-... 

Fig. 10 Fragment of crystal structures of tetracyanopyrazine complexes with halides showing coordination of anions to four, three or two acceptor moieties in Bu4N+[C1, (TCP)4] (a), Et4N+[(Br )2, (TCP)3] (b) and Bu4N+[r, (TCP)] (c) salts, respectively [23]...

Fig. 13 a Location of the halide anions above the tetracyanopyrazine (o) and tetracyano-benzene ( ) ir-systems (adapted from [24]) in comparison with b the LUMO shape of the TCP acceptor... 

Tetracyano ligands have been used to bridge between four Ru(NH3)5 moieties. The complexes [ Ru(NH3)5 4(/i-L)] + (L = tetracyanoethene, tetracyano-p-quinodimethane, 1,2,4,5-tetracyano-benzene, 2,3,5,6-tetracyanopyrazine) exhibit intense, long-wavelength electronic absorptions. Oxidation to [ Ru(NH3)5 4(yU-L)] °" " and reduction to [ Ru(NH3)5 4(//-L)] + and [ Ru(NH3)5 4-(/i-L)] + can readily be achieved. The species are fully delocalized with partially reduced ligands or partially oxidized Ru centers. Treatment of [5,10,15,20-tetrakis(4-cyanophenyl)porphyrinato] cobalt(II) or [5,10,15,20-tetrakis(4-cyano-2,6,-dimethylphenyl)porphyrinato]cobalt(II) with [Ru-(NH3)5(0S02CF3)] introduces cyano-bound pendant Ru (NH3)5 groups to the porphyrinato complexes. ... 

Other possible pyrazines, 2,3,5,6-tetracyanopyrazine (59) and 2-hydroxy-3,5,6-tricyanopyrazine (68) were probably formed but were not isolated (74JOC1235). 

E. Initial Displacement of Cyano Groups of 2-Amino-3,5,6-tricyanopyrazine and 2,3,5,6-Tetracyanopyrazine... 

Tetracyanopyrazine has been reported to react with liquid ammonia in tetra-hydrofuran to give 2,6-diamino-3,5-dicyanopyrazine (1180, 1182), and with dimethylamine in tetrahydrofuran at 0° to give 2,3,5-tricyano-6-dimethylamino-pyrazine (97.7%) (158), and this on treatment with ammonia in tetrahydrofuran gave 2-amino-3,5-dicyano-6-dimethylaminopyrazine (89%) (158). 

Tetracyanopyrazine with liquid ammonia in tetrahydrofuran formed 2,6-diamino-3,5-dicyanopyrazine (1180, 1182), and tetracyanopyrazine with piperazine similarly gave 2,6-dicyano-3,5-dipiperazin-l -ylpyrazine (1182). 

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