Recycling Organoiridium Waste to [(1,5-Cyclooctadiene)IrCl].

We report the first process for iridium element recovery from organoiridium waste that is quantitative, pyrolysis-free, and generates no iridium metal. The key step is oxidative degradation of the waste by bleach to crude iridium(IV) hydroxide. Its treatment with hydrazine and then hydrogen peroxide gives synthetically important hexachloroiridic acid, which is converted to [(1,5-cyclooctadiene)IrCl] in 87% yield.

Pressurized Formic Acid Dehydrogenation: An Entropic Spring Replaces Hydrogen Compression Cost.

Formic acid is unique among liquid organic hydrogen carriers (LOHCs), because its dehydrogenation is highly entropically driven. This enables the evolution of high-pressure hydrogen at mild temperatures that is difficult to achieve with other LOHCs, conceptually by releasing the "spring" of energy stored entropically in the liquid carrier. Applications calling for hydrogen-on-demand, such as vehicle filling, require pressurized H.

Synthesis of 1,4-Diazacycles by Hydrogen Borrowing.

We report the syntheses of 1,4-diazacycles by diol-diamine coupling, uniquely made possible with a (pyridyl)phosphine-ligated ruthenium(II) catalyst (). The reactions can exploit either two sequential -alkylations or an intermediate tautomerization pathway to yield piperazines and diazepanes; diazepanes are generally inaccessible by catalytic routes. Our conditions tolerate different amines and alcohols that are relevant to key medicinal platforms.

Heterobimetallic complexes of IrM (M = Fe, Co, and Ni) core and bridging 2-(diphenylphosphino)pyridine: electronic structure and electrochemical behavior.

Three complexes based on an Ir-M (M = Fe, Co, and Ni) heterobimetallic core and 2-(diphenylphosphino)pyridine (PhPPy) ligand were synthesized via the reaction of trans-[IrCl(CO)(PhPPy)] and the corresponding metal chloride. Their structures were established by single-crystal X-ray diffraction as [Ir(CO)(μ-Cl)(μ-PhPPy)FeCl]·2CHCl (2), [IrCl(CO)(μ-PhPPy)CoCl]·2CHCl (3), and [Ir(CO)(μ-Cl)(μ-PhPPy)NiCl]·2CHCl (4). Time-dependent DFT computations suggest a donor-acceptor interaction between a filled 5d orbital on iridium and an empty orbital on the first-row metal atom, which is supported by UV-vis studies.

Ruthenium Catalyzed Tandem Pictet-Spengler Reaction.

We report a pyridyl-phosphine ruthenium(II) catalyzed tandem alcohol amination/Pictet-Spengler reaction sequence to synthesize tetrahydro-β-carbolines from an alcohol and tryptamine. Our conditions use a Lewis acid cocatalyst, In(OTf), that is compatible with typically amination and an Pictet-Spengler cyclization. This method proceeds well with benzylic alcohols, heterocyclic carbinols, and aliphatic alcohols.