The Roles of Molecular Concavities in the Hierarchical Self-Assembly of Giant Tetrahedra for CO Uptake.

Giant tetrahedral molecules have sparked significant interest in the past decade due to their unique and diverse supramolecular nanostructures. The longer and bulkier peripheral substituents create deep molecular concavities and thus contribute to the different self-assembly behaviors compared to the conventional small tetrahedral molecules. In this study, a molecular giant tetrahedra, TetraNDI, was synthesized to investigate the important roles of the molecular concavities in the self-assembly mechanism.

Coordination Chemistry and Reactivity of a Lewis Acidic Di-Zinc Framework Supported by Bisphenoxymethanone Ligands.

We present the synthesis, structural characterization, and reactivity studies of a tetra-zinc complex supported by the bisphenoxymethanone ligands and its transformation into various di-zinc architectures. Our findings highlight the potential of these complexes in molecular recognition, supramolecular chemistry, and catalysis.

A Bis-Cyclopentadienyl Ligand-Supported Di-Iron Trihydride Motif as a Synthon for Access to Heterobimetallic Trinuclear Complexes.

Herein, we report the synthesis of a flexible bis-cyclopentadienyl ligand (the doubly deprotonated form of (1,3-bis(2,4-di--butylcyclopentadienyldimethylsilyl)benzene)), demonstrating its ability to stabilize a series of di-iron hydrido complexes. Notably, this ligand facilitates the isolation of an unprecedented anionic cyclopentadienyl ligand-supported di-iron trihydride complex, (), functioning as a synthon for the [Fe(μ-H)] core and providing access to heterobimetallic complexes - with coinage metals.

A Concise Route to Keto-Bridged Polyphenols by Photo-Fries Rearrangement in Flow.

Described is a new synthetic route to bis(2-hydroxy-3,5-di-t-butylphenyl)methanone and its derivatives. The combined esterification/photo-Fries rearrangement approach enables a modular preparation of keto-bridged polyphenols. This protecting group-free process is highly atom- and step-economic, and a scalable production was easily achieved in the continuous-flow mode.

Crystal structure of the α-ketoglutarate-dependent non-heme iron oxygenase CmnC in capreomycin biosynthesis and its engineering to catalyze hydroxylation of the substrate enantiomer.

CmnC is an α-ketoglutarate (α-KG)-dependent non-heme iron oxygenase involved in the formation of the l-capreomycidine (l-Cap) moiety in capreomycin (CMN) biosynthesis. CmnC and its homologues, VioC in viomycin (VIO) biosynthesis and OrfP in streptothricin (STT) biosynthesis, catalyze hydroxylation of l-Arg to form β-hydroxy l-Arg (CmnC and VioC) or β,γ-dihydroxy l-Arg (OrfP). In this study, a combination of biochemical characterization and structural determination was performed to understand the substrate binding environment and substrate specificity of CmnC.

Access to Monomeric Lead(II) Hydrides with Remarkable Thermostability and Their Use in Catalytic Hydroboration of Carbonyl Derivatives.

We report on the remarkable stability of unprecedented, monomeric lead(II) hydrides (), where = 2,6-bis(3,5-diphenylpyrrolyl)pyridine and = (18-crown-6)potassium or ([2.2.2]-cryptand)potassium.

Isolable Tin(II) Hydrides Featuring Sterically Undemanding Pincer-Type Ligands and Their Dehydrogenative Sn-Sn Bond Forming Reactions to Distannynes Promoted by Lewis Acidic Tri--butylborane.

Unlike isolable tin(II) hydrides supported by bulky ligands reported in the literature, this research describes the synthesis and characterization of thermally stable tin(II) hydrides () and () stabilized by sterically undemanding N,N,N-coordinating pincer-type ligands ( = 2,5-dipyridyl-3,4-diphenylpyrrolato; = 2,5-bis(6-methylpyridyl)pyrrolato). The results from previous reports reveal that attempts to access tin(II) hydrides containing less-bulky ligands have had limited success, and decomposition to tin(I) distannynes often occurs. The key to the successful isolation of and is the identification of the role of Lewis acidic BBu, generated upon delivering hydride from commonly used hydride reagents M[BBuH] ("selectrides", M = Li or K).

Linear, mixed-valent homocatenated tri-tin complexes featuring Sn-Sn bonds.

A series of tri-tin complexes (LPhSn)3X with triple-decker structures (LPh = 2,5-di(o-pyridyl)-3,4-diphenylpyrrolate; X = Cl, AlCl4, OTf, and PF6) was synthesized by reducing LPhSnCl with LiBsBu3H and subsequent reactions. Structural characterization of (LPhSn)3Cl revealed a Sn-Sn-Sn core, and DFT calculations suggest that its HOMO is primarily σ-bonding along the tri-tin framework. (LPhSn)3Cl reacts with W(CO)5THF to afford (LPhSn)2(W(CO)5)2 and LPhSnCl, implying that (LPhSn)3Cl may exhibit dynamic behavior in solution.

Synthesis, structures, and reactivity studies of cyclometalated N-heterocyclic carbene complexes of ruthenium.

An unusual cyclometalation reaction results from a C-C bond activation in Cp*(IPr)RuCl to give Cp*(IPr')Ru(L) featuring a NHC-C(sp2) chelating ligand (5-L; L = propene, N2; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; IPr' = 1-(6-isopropylphenyl)-3-(2,6-diisopropylphenyl)imidazol-2-ylidene). DFT calculations were employed to elucidate the C-C bond activation pathway. Reactions of cyclometalated ruthenium complexes bearing NHC-C(sp2) and NHC-C(sp3) ligands (5-L and Cp*(IXy-H)Ru(N2), 1a, respectively where IXy = 1,3-bis(2,6-dimethylphenyl)-imidazol-2-ylidene; IXy-H is the deprotonated form of (IXy)) are reported.

An N-heterocyclic carbene ligand promotes highly selective alkyne semihydrogenation with copper nanoparticles supported on passivated silica.

We report a surface organometallic route that generates copper nanoparticles (NPs) on a silica support while simultaneously passivating the silica surface with trimethylsiloxy groups. The material is active for the catalytic semihydrogenation of phenylalkyl-, dialkyl- and diaryl-alkynes and displays high chemo- and stereoselectivity at full alkyne conversion to corresponding ()-olefins in the presence of an N-heterocyclic carbene (NHC) ligand. Solid-state NMR spectroscopy using the NHC ligand C-labeled at the carbenic carbon reveals a genuine coordination of the carbene to Cu NPs.

Multishelled CaO Microspheres Stabilized by Atomic Layer Deposition of Al O for Enhanced CO Capture Performance.

CO capture and storage is a promising concept to reduce anthropogenic CO emissions. The most established technology for capturing CO relies on amine scrubbing that is, however, associated with high costs. Technoeconomic studies show that using CaO as a high-temperature CO sorbent can significantly reduce the costs of CO capture.

Pairwise hydrogen addition in the selective semihydrogenation of alkynes on silica-supported Cu catalysts.

Mechanistic insight into the semihydrogenation of 1-butyne and 2-butyne on Cu nanoparticles supported on partially dehydroxylated silica (Cu/SiO) was obtained using parahydrogen. Hydrogenation of 1-butyne over Cu/SiO yielded 1-butene with ≥97% selectivity. The surface modification of this catalyst with tricyclohexylphosphine (PCy) increased the selectivity to 1-butene up to nearly 100%, although at the expense of reduced catalytic activity.

Silica-Supported Cu Nanoparticle Catalysts for Alkyne Semihydrogenation: Effect of Ligands on Rates and Selectivity.

Narrowly dispersed, silica-supported Cu nanoparticles (ca. 2 nm) prepared via surface organometallic chemistry from a mesityl complex [CuMes] are highly active for the hydrogenation of a broad range of alkynes. High-throughput experimentation allows for identifying the optimal ligand and reaction conditions to turn these supported Cu nanoparticles into highly chemo- and stereoselective catalysts for the preparation of Z-olefins (overall, 23 examples).

Donor-Promoted 1,2-Hydrogen Migration from Silicon to a Saturated Ruthenium Center and Access to Silaoxiranyl and Silaiminyl Complexes.

Masked silylene complexes Cp*(IXy-H)(H)RuSiH2R (R = Mes (3) and Trip (4); IXy = 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene; "IXy-H" is the deprotonated form of IXy) exhibit metallosilylene-like (LnM-Si-R) reactivity, as observed in reactions of nonenolizable ketones, enones, and tosyl azides, to give unprecedented silaoxiranyl, oxasilacyclopentenyl, and silaiminyl complexes, respectively. Notably, these silicon-containing complexes are derived from the primary silanes MesSiH3 and TripSiH3 via activation of all three Si-H bonds. DFT calculations suggest that the mechanism of formation for the silaoxiranyl complex Cp*(IXy)(H)2Ru-Si(OCPh2)Trip (6) involves coordination of benzophenone to a silylene silicon atom, followed by a single-electron transfer in which Si-bonded, non-innocent benzophenone accepts an electron from the reactive, electron-rich ruthenium center.

The Ruthenostannylene Complex [Cp*(IXy)H2 Ru-Sn-Trip]: Providing Access to Unusual Ru-Sn Bonded Stanna-imine, Stannene, and Ketenylstannyl Complexes.

Reactivity studies of the thermally stable ruthenostannylene complex [Cp*(IXy)(H)2 Ru-Sn-Trip] (1; IXy=1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene; Cp*=η(5) -C5 Me5 ; Trip=2,4,6-iPr3 C6 H2 ) with a variety of organic substrates are described. Complex 1 reacts with benzoin and an α,β-unsaturated ketone to undergo [1+4] cycloaddition reactions and afford [Cp*(IXy)(H)2 RuSn(κ(2) -O,O-OCPhCPhO)Trip] (2) and [Cp*(IXy)(H)2 RuSn(κ(2) -O,C-OCPhCHCHPh)Trip] (3), respectively. The reaction of 1 with ethyl diazoacetate resulted in a tin-substituted ketene complex [Cp*(IXy)(H)2 RuSn(OC2 H5 )(CHCO)Trip] (4), which is most likely a decomposition product from the putative ruthenium-substituted stannene complex.

1,2-hydrogen migration to a saturated ruthenium complex via reversal of electronic properties for tin in a stannylene-to-metallostannylene conversion.

An intramolecular 1,2(α)-H migration in a saturated ruthenium stannylene complex, to form a ruthenostannylene complex, involves a reversal of the role for a coordinated stannylene ligand, from that of an electron donor to an acceptor in the transition state. This change in the bonding properties for a stannylene group, with a simple molecular motion, lifts the usual requirement for generation of an unsaturated metal center in migration chemistry.

Cyclometalated N-heterocyclic carbene complexes of ruthenium for access to electron-rich silylene complexes that bind the Lewis acids CuOTf and AgOTf.

The synthesis of the cyclometalated complexes Cp*Ru(IXy-H) (2) [IXy = 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene; IXy-H = 1-(2-CH2C6H3-6-methyl)-3-(2,6-dimethylphenyl)imidazol-2-ylidene-1-yl (the deprotonated form of IXy); Cp* = η(5)-C5Me5] and Cp*Ru(IXy-H)(N2) (3) was achieved by dehydrochlorination of Cp*Ru(IXy)Cl (1) with KCH2Ph. Complexes 2 and 3 activate primary silanes (RSiH3) to afford the silyl complexes Cp*(IXy-H)(H)RuSiH2R [R = p-Tol (4), Mes (5), Trip (6)]. Density functional theory studies indicated that these complexes are close in energy to the corresponding isomeric silylene species Cp*(IXy)(H)Ru═SiHR.

A facile iodide-controlled fluorescent switch based on the interconversion between two- and three-coordinate copper(I) complexes.

The first paradigm of halide-controlled interconversion between two- and three-coordinate copper(i) complexes, [Cu(L(Ph))](ClO(4)) (1?ClO(4)) and [Cu(L(Ph))I] (2), where L(Ph) = 1,3-bis-(3,5-dimethyl-pyrazol-1-ylmethyl)-2-phenyl-2,3-dihydro-1H-perimidine, was presented, which can result in reversible fluorescence changes.

The first stereochemically nonrigid monomeric two-coordinate copper(I) complexes with homoleptic and heteroleptic "N2" donor set.

A novel set of stereochemically nonrigid monomeric two-coordinate copper(I) complexes, [Cu(eta(1)-H(2)CPz''(2))(2)]ClO(4) 1, [Cu(HPz'')(2)]ClO(4) 2, and [Cu(HPz'')(eta(1)-H(2)CPz''(2))]ClO(4) 3, where Pz'' = 3,5-di-tert-butylpyrazolyl, has been synthesized and characterized by X-ray diffraction and variable-temperature (1)H NMR spectroscopy. Based on the (1)H NMR line shape analysis of complexes 1 and 2, the intramolecular fluxional process was proposed for these two-coordinate copper(I) complexes. Also, the mixed ligand complex 3 shows that these two different dynamic binding modes of the coordinated HPz'' and H(2)CPz''(2) ligands can proceed simultaneously on a single copper(I) ion.

Proton-controllable fluorescent switch based on interconversion of polynuclear and dinuclear copper(II) complexes.

The first reversible interconversion process between a one-strand polymeric copper(II) complex {[Cu2(L1)2(ClO4)2](ClO4)2}n (1) and a dicopper(II) helicate [Cu2(L1-2H)2] (2), proceeding via a deprotonation-protonation process, can transduce fluorescence and function as a fluorescent switch simply by introducing a one fiftieth equivalent of coumarine 343 anion, a fluorophore.