Characterization of Novel Polyhalogen Monoanions

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The present proposal aims at providing a variety of experimental spectroscopic tools comple-mented by state-of-the-art quantumchemical calculations guiding the preparation of novel polyhalogen anions which are challenging but instructive to study undermatrixisolation conditions and which are expected to build up noncovalent networks. There is a number of important questions regarding all these non-covalent interactions, such as how strong they are and what are the main contributions, how these change with the conformation, and how these are affected by crystal packing effects etc, and finally, how can this knowledge be used to design novel structures and applications. A primary goal is the preparation of such novel weakly bound systems under matrixisolation conditions which allows a rigorous time independent spectroscopic characterization of effectively isolated molecular systems (pseudo-gas-phase conditions) at very low temperatures (<20 K). The experimental results obtained from sufficiently simple but highly challenging systems such as [F5]-, [Cl5]-, and analogous interhalide counterparts such as [F(Cl2)2]-, [Cl(Br2)2]-, [F(Br2)2]- will develop our understanding of noncovalent interaction in these electron-rich systems and will be used to validate state-of-the-art quantum chemical calculations. Beside spectroscopy on effectively isolated molecular species we intend to prepare novel polyhalogene monoanions also in bulk quantities, such as [Cln]-; n=5,7,9 and new interhalogen monoanions like [F(Br2)2]- or [Cl(Br2)2]-. This subproject will elucidate the transition from isolated molecular species to bulk quantities in solution, and to extended networks in the solid state. The preparation of novel species will be guided by a variety of available spectroscopic techniques such as low-temperature IR, UV/VIS, and in situ Raman spectroscopy, as well as single crystal x-ray structure determination, and their potential applications will be explored in combination with high-level quantum chemical studies.