Cooperative Carbon Dioxide Capture in Diamine-Appended Magnesium-Olsalazine Frameworks.

Diamine-appended Mg(dobpdc) (dobpdc = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) metal-organic frameworks have emerged as promising candidates for carbon capture owing to their exceptional CO selectivities, high separation capacities, and step-shaped adsorption profiles, which arise from a unique cooperative adsorption mechanism resulting in the formation of ammonium carbamate chains. Materials appended with ,-diamines featuring bulky substituents, in particular, exhibit excellent stabilities and CO adsorption properties. However, these frameworks display double-step adsorption behavior arising from steric repulsion between ammonium carbamates, which ultimately results in increased regeneration energies.

Reversible Alkyl-Group Migration between Iron and Sulfur in [FeS] Clusters.

Synthetic [FeS] clusters with Fe-R groups (R = alkyl/benzyl) are shown to release organic radicals on an [FeS]-R/[FeS] redox couple, the same that has been proposed for a radical-generating intermediate in the superfamily of radical -adenosyl-l-methionine (SAM) enzymes. In attempts to trap the immediate precursor to radical generation, a species in which the alkyl group has migrated from Fe to S is instead isolated. This S-alkylated cluster is a structurally faithful model of intermediates proposed in a variety of functionally diverse S transferase enzymes and features an "[FeS]-like" core that exists as a physical mixture of = 1/2 and 7/2 states.

Taming phosphorus mononitride.

Phosphorus mononitride (PN) only has a fleeting existence on Earth, and molecular precursors for the release of this molecule under mild conditions in solution have remained elusive. Here we report the synthesis of an anthracene-based precursor-an anthracene moiety featuring an azidophosphine bridge across its central ring-that dissociates into dinitrogen, anthracene and P≡N in solution with a first-order half-life of roughly 30 min at room temperature. Heated under reduced pressure, this azidophosphine-anthracene precursor decomposes in an explosive fashion at around 42 °C, as demonstrated in a molecular-beam mass spectrometry study.

Alleviating Strain in Organic Molecules by Incorporation of Phosphorus: Synthesis of Triphosphatetrahedrane.

Phosphatetrahedranes (BuCP) and (BuC)P were recently reported and represent the first tetrahedranes containing a mixed carbon/phosphorus core. Herein, we report that tetrahydrofuran (THF) solutions of the parent triphosphatetrahedrane HCP may be generated in 31% yield (NMR internal standard yield) by combining [Na(THF)][PNb(ODipp)] (Dipp = 2,6-diisopropylphenyl), INb(ODipp)(THF), and bromodichloromethane in thawing THF. While HCP was found to be stable in dilute THF solutions for extended periods of time, the concentration of the solution at -40 °C led to the formation of a black precipitate, which has been tentatively assigned as a polymerized form of HCP.

A Synthetic Model of Enzymatic [FeS]-Alkyl Intermediates.

Although alkyl complexes of [FeS] clusters have been invoked as intermediates in a number of enzymatic reactions, obtaining a detailed understanding of their reactivity patterns and electronic structures has been difficult owing to their transient nature. To address this challenge, we herein report the synthesis and characterization of a 3:1 site-differentiated [FeS]-alkyl cluster. Whereas [FeS] clusters typically exhibit pairwise delocalized electronic structures in which each Fe has a formal valence of 2.