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Molecularly defined and classical heterogeneous Mo-based metathesis catalysts are shown to display distinct and unexpected reactivity patterns for the metathesis of long-chain α-olefins at low temperatures (, JACS Au, 2 (3), ISSN:2691-3704

Molecularly defined and classical heterogenous Mo-based metathesis catalysts are shown to display dis-tinct and unexpected reactivity patterns for the metathesis of long-chain α-olefins at low temperatures (< 100 °C). Namely, catalysts based on supported Mo oxo species, whether prepared via wet impregnation or surface organometallic chemistry (SOMC), exhibit strong activity dependencies on the α-olefin chain length, with slower reaction rates for longer substrate chain lengths. In contrast, molecular and support-ed Mo alkylidenes are highly active and do not display such dramatic dependence on chain length. State-of-the-art 2D solid-state NMR analyses of post-metathesis catalysts, complemented by FTIR and molecular dynamics calculations, evidence that the activity decrease observed for supported Mo oxo catalysts relates to the strong adsorption of internal olefin metathesis products due to interactions with surface Si-OH groups. Overall, this study shows that in addition to the nature and the number of active sites, the metathesis rates and overall catalytic performance depend on product desorption, even in the liquid phase with non-polar substrates. This study further highlights the role of support and active site composition and dynamics on activity as well as the need to consider adsorption in catalyst design.

Metal-assisted salphen organic frameworks (MaSOFs) are known to possess high affinities to CO2 due to Lewis acidic metal sites and are therefore able to selectively adsorb CO2 over CH4 or N2. By al...

Oligoarenes are regarded as subunits of π-extended carbon nanoforms, such as graphene and nanotubes, with exceptional technological importance. Fused arenes can thus provide fundamental insight into the nature of the electronic properties of fused polyaromatic rings and pave the way for the design of extended graphene-like materials. However, large π-extended arenes often show low stability. Herein we report the straightforward preparation of linearly fused diphosphahexaarenes containing two six-membered phosphorus heterocycles. They are highly stable towards air, water, and light over months in both solution and the solid state. Single-crystal X-ray crystallography confirmed the molecular structure of all derivatives. Investigations of their optoelectronic properties revealed that the diphosphahexaarenes exhibit ambipolar redox behavior and high fluorescence quantum yields. Embedding six-membered phosphorus rings into large acenes thus opens up new opportunities for the investigation of polyaromatic systems.