Synthesis of Collidine from Dinitrogen via a Tungsten Nitride.

The synthesis of pyridines from dinitrogen in homogeneous solution is known to be challenging considering that an N cleavage step needs to be combined with two N-C coupling steps. Herein, a tungsten complex bearing a tailor-made 2,2'-(BuAs)-substituted tolane ligand scaffold was shown to split N to afford the corresponding tungsten nitride, which is not the case for the corresponding (PrAs)-substituted derivative. The former nitride was then reacted with 2,4,6-trimethylpyrylium triflate, which led to the formation of a tungsten oxo complex, along with collidine.

To Split or Not to Split: [AsCCAs]-Coordinated Mo, W, and Re Complexes and Their Reactivity toward Molecular Dinitrogen.

Molybdenum, tungsten, and rhenium halides bearing a 2,2'-(PrAs)-substituted diphenylacetylene ([AsCCAs], ) were prepared and reduced under an atmosphere of dinitrogen in order to activate the latter substrate. In the case of molybdenum, a diiodo () and a triiodo molybdenum precursor () were equally suited for reductive N splitting, which led to the isolation of [AsCCAs]Mo≡N(I) () in each case. For tungsten, [AsCCAs]WCl () was reduced under N to afford {[AsCCAs]WCl}(N) (), which is best described as a dinuclear πδ-configured μ-(η: η)-N-bridged dimer.

The Role of Hypoxia-Inducible Factor 1 Alpha in Acute-on-Chronic Liver Failure.

Acute-on-chronic liver failure (ACLF) is associated with increased mortality. Specific therapy options are limited. Hypoxia-inducible factor 1 alpha (HIF-1α) has been linked to the pathogenesis of chronic liver disease (CLD), but the role of HIF-1α in ACLF is poorly understood.

[AsCCAs]-Coordinated Rhenium Hydrides and Their Reactivities Toward Unsaturated Hydrocarbons, Heterocumulenes, and CO.

An [AsCCAs] ligand featuring a central alkyne and two flanking arsenic donors was employed for the synthesis of a trihydrido rhenium complex, while the corresponding phosphorus ligand was shown to be less suited. The reactivity of the former trihydride [AsCCAs]ReH () was examined in detail, which revealed that two alternative reaction channels may be entered in dependence of the substrate. Upon reaction of with PhC≡CPh, ethylene, and CS, monohydrides of the general formula [AsCCAs]Re(L)H with L = η-PhC≡CPh (), η-HC═CH (), and η-CS () were formed along with H.