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End date: 2014 Ă— Start date: 2014 Ă— Publisher: Cambridge : RSC Ă— WGL Institute: LIKAT Ă—

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    The effect of supported MoOX structures on the reaction pathways of propene formation in the metathesis of ethylene and 2-butene
    (Cambridge : RSC, 2014) Hahn, T.; Kondratenko, E.V.; Linke, D.
    The kind of surface MoOX structures on Al2O3–SiO2 was found to determine propene selectivity in the metathesis of ethylene and 2-butene. Compared to isolated tetrahedral MoOX species, their polymerized octahedral counterparts show significantly lower activity for isomerisation of 2- to 1-butene thus hindering non-selective metathesis of these butenes. In addition, they reveal higher ability to engage ethylene in propene formation.
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    Probing the second dehydrogenation step in ammonia-borane dehydrocoupling: characterization and reactivity of the key intermediate, B-(cyclotriborazanyl)amine-borane
    (Cambridge : RSC, 2014) Kalviri, Hassan A.; Gärtner, Felix; Ye, Gang; Korobkov, Ilia; Baker, R. Tom
    While thermolysis of ammonia-borane (AB) affords a mixture of aminoborane- and iminoborane oligomers, the most selective metal-based catalysts afford exclusively cyclic iminoborane trimer (borazine) and its B–N cross-linked oligomers (polyborazylene). This catalysed dehydrogenation sequence proceeds through a branched cyclic aminoborane oligomer assigned previously as trimeric B-(cyclodiborazanyl)amine-borane (BCDB). Herein we utilize multinuclear NMR spectroscopy and X-ray crystallography to show instead that this key intermediate is actually tetrameric B-(cyclotriborazanyl)amine-borane (BCTB) and a method is presented for its selective synthesis from AB. The reactivity of BCTB upon thermal treatment as well as catalytic dehydrogenation is studied and discussed with regard to facilitating the second dehydrogenation step in AB dehydrocoupling.