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doi: 10.1002/anie.199213993pmid: N/A
Stilbenes and compounds containing stilbene units in their structures form the material basis for numerous research projects in photophysics and photochemistry. Moreover, because these compounds are easy to synthesize and are thermally and chemically stable, they are taking on an increasingly prominent role in the area of materials science investigations into optical, electrical, and optoelectronic properties. In accordance with the interdisciplinary nature of such studies, this article aims to provide a bridge extending from molecular theory and photophysical measurements, through preparative applications, to material effects and their potential technical applications.
doi: 10.1002/anie.199214211pmid: N/A
The study of non‐natural products has led to a broad understanding of bonding and reactivity in organic chemistry. Many times, compounds thought impossible have been realized in the course of such studies. Cubane, a landmark in the world of “impossible” compounds, has been found to have a rich chemistry, full of the unexpected. The recent renaissance of cubane chemistry, triggered by potential applications of the system to the production of high‐energy fuels and the like, has led to many discoveries including the first methods for systematic substitution on strained, saturated systems and a new process for the metalation of arenes, ortho magnesiation. Reactive intermediates with exceptional bonding parameters have been uncovered and characterized including 1(9)‐homocubene, the most twisted olefin; cubene, the most pyramidalized olefin; cubyl cation, once the “least likely” cation; cubylmethyl radical, a saturated radical that rearranges on the picosecond timescale; and many other extraordinary species. There is certainly good reason to believe that future work in the cubane arena will be at least as productive (probably more so), and that it will help develop a deeper understanding of chemistry.
Köhler, Jürgen; Svensson, Gunnar; Simon, Arndt
doi: 10.1002/anie.199214371pmid: N/A
Metal clusters, discrete or condensed, are characteristic of the structures of many compounds which contain transition metals in low oxidation states. The highly reduced oxoniobates support the concept of condensed clusters. They contain Nb6O12 clusters which are either isolated or linked at the apices of the Nb6 octahedra to form oligomeric chains or networks. The analysis of the bonding relationships allows the identification of different types of Nb atoms and thus the quantitative prediction of valence electron concentrations for finite or infinite structures composed of these condensed M6X12 clusters.
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