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  • Author: Hermann Irngartinger x
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The crystal structure and the X—X difference electron density distribution of 1,3-bis(diisopropylamino)-1,3,dihydro-1,3-diborete (1) has been determined at the temperature of 107 K. Both π-electrons of the folded aromatic four membered ring system (folding angle 47.6°) are uniformly distributed on the four ring bonds with equal lengths (B—C 1.524 A). These bonds are significantly bent.

The 2,5-bis(2-arylvinyl)-1,4-benzoquinones 1a-1e are formed from hydrolysis of their corresponding ketals 5 which are generated by anodic oxidation of the corresponding 1,4-dimethoxybenzene derivatives 4. The crystal structures of the quinone compounds 1a, 1d and 1e have been determined by X-ray analyses. The bond lengths of the quinone system are influenced by polar resonance structures. An α-type packing mode is observed for the three crystal structures of compounds 1. The vinylic double bonds have short intermolecular distances (1a: 4.417(5), 1d: 3.653(2), 1e: 4.224(5) Å). Only the crystals of 1d with the shortest contacts are photoreactive

The cyclic voltammograms of 1-cyano-2-hydroxy-1,2-dihydrofullerene derivatives indicate a complex redox behavior. The first reduction peak of these new compounds is at less negative values compared to the parent [60]fullerene. This is a consequence of the two electronwithdrawing groups, which are attached directly to the C60 moiety.

Suitable protected 4,4a-anhydro-cyclopentane derivatives have been used for the straightforward of cyclopentanoid nucleoside precursors. Thus, by simple transformations nucleoside precursors modified at the positions C(4), C(4a) and C(4,4a) as well as side-chain modified derivatives were accessible. The structures of the key intermediates were determined by xray analyses.