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Unusual strength and directionality for the charge-transfer motif (established in solution) are shown to carry over into the solid state by the facile synthesis of a series of robust crystals of the [1:1] donor/acceptor complexes of carbon tetrabromide with the electron-rich halide anions (chloride, bromide, and iodide). X-ray crystallographic analyses identify the consistent formation of diamondoid networks, the dimensionality of which is dictated by the size of the tetraalkylammonium counterion. For the tetraethylammonium bromide/carbon tetrabromide dyad, the three-dimensional (diamondoid) network consists of donor (bromide) and acceptor (CBr(4)) nodes alternately populated to result in the effective annihilation of centers of symmetry in agreement with the sphaleroid structural subclass. Such inherently acentric networks exhibit intensive nonlinear optical properties in which the second harmonics generation in the extended charge-transfer system is augmented by the effective electronic (HOMO-LUMO) coupling between contiguous CBr(4)/halide centers.

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A single element of chirality determines the configuration of the three newly formed stereogenic centers in the title reaction [Eq. (a)]. In particular, large (R = SiMe2Ph,tBu) and polar (R = OMe) substituents induce good diastereoselectivities. Simple ring‐opening reactions facilitate a stereoselective approach to acyclic products.

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Nur ein Chiralitätszentrum steuert in der Titelreaktion die Konfiguration der drei neugebildeten stereogenen Zentren [Gl.(a)]. Insbesondere große (R = SiMe2Ph, tBu) und polare Substituenten (R = OMe) führen zu hohen Diastereoselektivitäten. Durch einfache Ringöffnungsreaktionen sind über diese Methode auch acyclische Produkte stereoselektiv zugänglich.

o-Alkoxy-substituted l-oxa-3,5-diazahexatrienes ( 5 ) , l-oxa-3,5,7-triazaoctatetraenes (?), and l-oxa-3,5,7,9-tetraazadecapentaenes (9) were synthesized by condensation of 1,3-dialkoxy-2-azapropenylium salts (3) or 1,5-dialkoxy-2,4-diazapentadienylium salts (8) with N-acyl-and N-alkoxycarbonylamidines (4). It is the nature of the leaving group which mainly determines the chain length of the products obtained.-Compounds ? show ring-chain tautomerism involving the cyclic form 6 in dependence of the substitution pattern. All o-alkoxy substituted oligonitriles 5, 7, and 9 may easily converted to the corresponding o-amino compounds 11, 14, and 15 by reaction with secondary amines 10. Reaction of 5a, b with the primary amine 12 leads to the triazinone 13. The lithiated ketimine 16 converts 5b and 7d to the corresponding l-oxa-3,5,7-triazaoctatetraenes 17 and l-oxa-3,5,7,9-tetraazadecapentaenes 18. Helical geometries dominate the structures of the new oligonitriles in the crystalline state as derived from X-ray analyses of compounds 5a, 7c, 9a, and 18. Push-pull substitution effects, which should be strong in the amino derivatives 11, 14, and 15, have no significant influence on the structure of the oligonitriles. Ph Ph R BF; 3 4a, Sa, 6a: R = OMe 4b, 5b, 6 b R = OEt 4c, Sc, 7c: R =p-To1