N Dissociation vs Reversible 1,2-Methyl Migration in PCP Cobalt(I) Complexes in the Stereoselective Isomerization () of Allyl Ethers.

With growing efforts pushing toward sustainable catalysis, using earth-abundant metals has become increasingly important. Here, we present the first examples of cobalt PCP pincer complexes that demonstrate dual stereoselectivity for allyl ether isomerization. While the cationic cobalt complex [((PCP)Co)-μ-N][BAr ] () mainly favors the -isomer of the enol ether, the corresponding methyl complex [(PCP)CoMe] () mostly gives the -isomer.

The Crystal Structure of Dodecahedral Ba Hexa-Perchlorate Complex Tetrakis 1-N-Propyl-3-vinyl-imidazol-1-ium·Barium Hexa-Perchlorate.

In cold methanol, energetic ionic liquid 1-n-propyl-3-vinyl-imidazol-1-ium perchlorate, , crystallizes in the presence of excess Ba(ClO), , into tetrakis 1-propyl-3-vinyl-imidazol-1-ium·barium hexa-perchlorate, . Crystals of , with molecular formula (CHN)·BaClO, are colorless and monoclinic, with space group P2/c. The crystal structure is characterized by a dodecahedral coordination around the barium atom, with each perchlorate chelating Ba in a κO,O' fashion, and the Ba(ClO) anion is surrounded by four imidazolium cations.

Triscyanocorrole, the Newest and Most Intriguing Member of the C-Substituted Corrole Family.

Considering the potential advantages of minimally sized corroles for diverse applications, this study reports a facile access to cyano-substituted derivatives via a rare CF/CN conversion. Investigation of the fully characterized gallium, phosphorus, and cobalt complexes discloses multiple effects of the meso-nitrile groups attached to the macrocycle. This corrole appears to be the most electron poor derivative which comes into play in the redox potentials of the corresponding complexes.

Unique Crystal Structure of a Self-Assembled Dinuclear Cu Peptoid Reveals an Unusually Long Cu···Cu Distance.

Studies on a series of molecular dicopper peptoid complexes showed that the Cu···Cu distances measured in X-ray single-crystal diffraction are typically in the range of 4.2-6.9 Å.

Triazenolysis of alkenes as an aza version of ozonolysis.

Alkenes are broadly used in synthetic applications, thanks to their abundance and versatility. Ozonolysis is one of the most canonical transformations that converts alkenes into molecules bearing carbon-oxygen motifs via C=C bond cleavage. Despite its extensive use in both industrial and laboratory settings, the aza version-cleavage of alkenes to form carbon-nitrogen bonds-remains elusive.

Redox Active Ligands for Catalyzing the Hydrogen Evolution Reaction.

Boron subphthalocyanines with chloride and fluoride axial ligands and three antimony complexes chelated by corroles that differ in size and electron-richness were examined as electrocatalysts for reduction of protons to hydrogen. Experiment- and computation-based investigations revealed that all redox events are ligand-centered and that the meso-C of the corroles and the peripheral N atoms of the subphthalocyanines are the largely preferred proton-binding sites.

Surprising Route to a Monoazaporphyrin and Full Characterization of Its Complexes with Five Different 3d Metals.

In the search for mild agents for the oxidative cyclization of tetrapyrromethane to the corresponding corrole, we discovered a route that leads to a monoazaporphyrin with three -CF groups. Optimization studies that allowed access to appreciable amounts of this new macrocycle paved the way for the preparation of its cobalt, copper, nickel, zinc, and iron complexes. All complexes were fully characterized by various spectroscopic methods and X-ray crystallography.

Temperature Dependence of the Ring Opening of Cyclopropene Imines on Thorium Metallocenes.

The reactions of two highly strained cyclopropenimine ligands and ( = -tetraisopropyl-3-iminocycloprop-1-ene-1,2-diamine, = -tetracyclohexyl-3-iminocycloprop-1-ene-1,2-diamine) with three thorium precursors Cp*ThCl, Cp*Th(Cl)(CH), and Cp*Th(CH) were studied. At -20 °C, and react with Cp*ThCl to form ( = Cp*ThCl(L1H)) and ( = Cp*ThCl(L2H)), respectively, where the neutral ligand coordinates to the thorium metal center. Coordination of the ligand to the thorium metal center introduces aromaticity at the cyclopropene ring of the ligand.

Nitrenium ions as new versatile reagents for electrophilic amination.

Herein we report the utilization of N-heterocyclic nitrenium ions - easily prepared, bench-stable and non-oxidating nitrogen sources for the efficient electrophilic amination of aliphatic and aromatic organometallic nucleophiles, towards the facile and general preparation of primary amines. To this end, a plethora of abundant organolithium and organomagnesium reagents were combined with nitrenium salts to generate a variety of previously unexplored -alkyl and -aryl triazanes. Through the simple hydrogenolysis of these relatively stable triazanes, we have prepared a diverse scope of primary amines, including linear and branched aliphatic as well as (hetero)aromatic amines possessing various stereo-electronic substituents.

Reversible Reactions of Nitric Oxide with a Binuclear Iron(III) Nitrophorin Mimic.

Construction of functional synthetic systems that can reversibly bind and transport the most biologically important gaseous molecules, oxygen and nitric oxide (NO), remains a contemporary challenge. Myoglobin and nitrophorin perform these respective tasks employing a protein-embedded heme center where one axial iron site is occupied by a histidine residue and the other is available for small molecule ligation, structural features that are extremely difficult to mimic in protein-free environments. Indeed, the hitherto reported designs rely on sophisticated multistep syntheses for limiting access to one of the two axial coordination sites in small molecules.

The First Planar, Not Twisted, Distannene - A Structural Alkene Analog. Synthesis, Isolation and X-ray Crystallography Characterization.

The tetrasilyl-substituted distannene, (tBu HSi) Sn=Sn(SiHtBu ) 6, was synthesized by mild thermolysis (70 °C in hexane) of tris(di-tert-butyl-hydridosilyl)stannane 4. The X-ray crystallography structure of 6 reveals the following unusual structural properties: a planar geometry around both Sn atoms (Σ∡Sn=359.87°), a non-twisted Sn=Sn double bond, and the shortest Sn=Sn double bond of 2.

Catalytic regeneration of metal-hydrides from their corresponding metal-alkoxides the hydroboration of carbonates to obtain methanol and diols.

Thorium complexes decorated with 5-, 6-, and 7-membered -heterocyclic iminato ligands containing mesityl wingtip substitutions have been synthesized and fully characterized. These complexes were found to be efficient in the hydroboration of cyclic and linear organic carbonates with HBpin or 9-BBN promoting their decarbonylation and producing the corresponding boronated diols and methanol. In addition, the hydroboration of CO breaks the molecule into "CO" and "O" forming boronated methanol and pinBOBpin.

Catalytic Atroposelective Aerobic Oxidation Approaches to Axially Chiral Molecules.

A copper and chiral nitroxide co-catalyzed aerobic enantioselective oxidation process has been developed that allows access to axially chiral molecules. Two complementary atroposelective approaches, oxidative kinetic resolution (OKR) and desymmetrization, were studied using ambient air as the stoichiometric terminal oxidant. OKR of --arylpyrrole alcohols and -biaryl alcohols affords the optically pure compounds with up to 3.

Facile Synthesis of an Octagermacubane with Two Three-Coordinate Germanium(0) Atoms and its Unique Radical Anion.

Thermolysis of a 1 : 1 mixture of tris(di-tert-butylmethylsilyl)germane 9 and bis(di-tert-butylmethylsilyl)germane 17 at 100 °C produces unexpectedly octagermacubane 18, having two 3-coordinate Ge atoms (40 % yield). 18 was characterized by X-ray crystallography and it is a singlet biradical (according to DFT quantum mechanical calculations and the absence of an EPR signal). Reactions of 18 with CH Cl and H O yield the novel dichloro-octagermacubane 24 and hydroxy-octagermacubane 25, respectively.

2-Nitro-cyclopropyl-1-carbonyl Compounds from Unsaturated Carbonyl Compounds and Nitromethane via Enolonium Species.

2-Nitrocyclopropanes bearing ketones, amides, esters, and carboxylic acids in the 1 position may be accessed as single diastereoisomers in one operation from the corresponding unsaturated carbonyl compounds. The source of the nitro-methylene component is nitromethane. The reaction proceeds at room temperature under mild conditions.

Multimodal Reactivity of N-H Bonds in Triazanes and Isolation of a Triazinyl Radical.

The employment of nitrogen Lewis acids based on nitrenium cations has been increasingly featured in the fields of main group chemistry and catalysis. A formally reduced form of nitrenium ─cyclic triazanes ─are intriguing chemical compounds, the chemistry of which is completely unexplored. In this work, we reveal that N-H-triazanes exhibit unusual N-H bond properties; namely, they can serve as protons, hydrides, or hydrogen atom donors.

Formation of distinct iron hydrides mechanistic divergence in directed C-H Bond activation of aryl ketones, esters and amides.

Directing groups play an important role in controlling the selectivity of C-H bond activation. Here we demonstrate that for iron, the nature of the directing group (, ketone, ester, or amide) influences the C-H activation process. In this study the C-H bond activation step either occurs with or without the assistance of the directing group resulting in distinct - and -isomers of the corresponding iron hydride.

Electronic Coupling and Electrocatalysis in Redox Active Fused Iron Corroles.

Conjugated arrays composed of corrole macrocycles are increasingly more common, but their chemistry still lags behind that of their porphyrin counterparts. Here, we report on the insertion of iron(III) into a β,β-fused corrole dimer and on the electronic effects that this redox active metal center has on the already rich coordination chemistry of [Htpfc] COT, where COT = cyclo-octatetraene and tpfc = tris(pentafluorophenyl)corrole. Synthetic manipulations were performed for the isolation and full characterization of both the 5-coordinate [Fetpfc(py)]COT and 6-coordinate [Fetpfc(py)]COT, with one and two axial pyridine ligands per metal, respectively.

Structural characterization and bioimaging of Zn using meta-benziporphodimethene analogue.

'Prevention is better than cure, especially when something has no cure.' Cancer, in most patients is detected at the stage beyond which it becomes noncurative. Therefore, the early detection of cancer cells can play a crucial role in enhancing the chances of a patient's survival.

Borate Buffer as a Key Player in Cu-Based Homogeneous Electrocatalytic Water Oxidation.

Borate buffer was found to have both structural and functional roles within a low-cost tri-copper electrocatalyst for homogeneous water oxidation that exhibits a high turnover frequency of 310 s . The borate buffer was shown to facilitate the catalytic activity by both bridging the three Cu ions and participating in O-O bond formation. Phosphate and acetate buffers did not show such roles, making borate a unique player in this catalytic system.

Amide bond hydrolysis of peptoids.

Incorporating a chiral non-coordinating substitution at the N-terminal end within peptoids facilitates regio-selective amide bond hydrolysis mediated by a transition metal ion and/or an acidic buffer as evident by X-ray crystallographic analysis, supported by ESI-MS. This opens up a new direction for peptidomimetic compounds towards future application in chemistry, biology and medicine.

Copper- and Chiral Nitroxide-Catalyzed Oxidative Kinetic Resolution of Axially Chiral -Arylpyrroles.

A readily prepared C-symmetric, α-hydrogen-substituted chiral hydroxylamine serves as a precatalyst to generate a chiral nitroxide . This chiral nitroxide catalyst in combination with a copper co-catalyst functions as an oxidant for an unprecedented enantioselective oxidative kinetic resolution (OKR) of racemic axially chiral -arylpyrrole alcohols using atmospheric oxygen as an environmentally friendly terminal oxidant. The OKR process provides the axially chiral -arylpyrroles in er up to 3.

Triazolium Salts as Lewis Acid Catalysts.

We describe a new type of nitrenium-based Lewis acids: tetraaryl-1,2,3-triazolium salts. These were fully characterized by NMR and X-ray crystallography. The Gutmann-Beckett acidity numbers were determined to be up to 35.

Synthesis of Genuine Germenyl Lithiums and the First Persistent Germenyl Radicals.

The first isolated genuine germenyl lithiums (R Si)(1-Ad)C=Ge(SiMetBu )(Li⋅2 L) (R Si=tBu MeSi, L=THF (1 a), or L=12-crown-4 (1 b) and R Si=tBuMe Si, L=THF (2 a), or L=12-crown-4 (2 b)), were synthesized by reaction of the corresponding acyl germanes 3 and 4, respectively, with tBu MeSiLi in THF at 70 °C. The novel 1 a and 2 b were characterized by NMR and UV/Vis spectroscopy, and also by X-ray crystallography (r(C=Ge)=1.865 Å for 1 a and 1.

Doubly Stimulated Corrole for Organelle-Selective Antitumor Cytotoxicity.

Balancing between safety and efficacy of cancer chemotherapeutics is achievable by relying on internal and/or external stimuli for selective and on-demand antitumor cytotoxicity. We now introduce the difluorophosphorus(V) corrole , a theranostic agent with a pH-sensitive -methylimidazole moiety. Structure/activity relationships, via comparison with the permanently charged and the lipophilic , uncovered the exceptional features of : nanoparticular and monomeric at neutral and low pH, respectively, 10-fold increased light-induced singlet oxygen production at acidic pH, internalization into malignant cells within minutes, and selective accumulation within lysosomes.