We report here on a new series of CO2-reducing molecular catalysts based Earth-abundant elements that are very selective for the production formic acid in dimethylformamide (DMF)/water mixtures (Faradaic efficiency 90 ± 10%) at moderate overpotentials (500–700 mV DMF measured middle catalytic wave). The [CpCo(PR2NR′2)I]+ compounds contain diphosphine ligands, PR2NR′2, with two pendant amine residues act as proton relays during CO2-reduction catalysis and tune their activity. Four different...

This works introduces hypervalent bis-catecholato silicon compounds as versatile sources of alkyl radicals upon visible-light photocatalysis. Using Ir[(dF(CF3)ppy)2(bpy)](PF6) (dF(CF3)ppy = 2-(2,4-difluorophenyl)-5-trifluoromethylpyridine, bpy bipyridine) catalytic photooxidant, a series radicals, including highly reactive primary ones can be generated and engaged in various intermolecular homolytic reactions. Based on cyclic voltammetry, Stern-Volmer studies, supported by calculations,...

Calculations suggest that complexes of borane with N-heterocyclic carbenes (NHC) have B-H bond dissocation energies more then 20 kcal/mol less than free borane, diborane, borane-THF, and related complexes. Values are in the range popular radical hydrogen atom donors like tin hydrides (70-80 kcal/mol). The resulting prediction NHC could be used as was verified by deoxygenations xanthates using either AIBN or triethylborane initiator.

Mechanistic questions concerning palladium and norbornene catalyzed aryl-aryl coupling reactions are treated in this paper: how aryl halides react with the intermediate palladacycles, formed by interaction of two catalysts an halide, what is rational explanation "ortho effect" (caused ortho substituent starting halide), which leads to a second molecule halide rather than aryl-norbornyl coupling. Two possible pathways have been proposed, one involving oxidative addition palladacycle, other...

Abstract Introduced in the late sixties, non‐innocent (or redox) ligands have been extensively studied for their unusual and intriguing chemical behavior. Their ability to delocalize and/or provide electrons metal center of organometallic complexes confers them undisputable interest has proved valuable development novel synthetic methodologies. This review will focus on chemistry applications low‐valent iron bearing potentially ligands. Because elusive nature these ligands, whenever...

Lying low: A lithiated unsubstituted N-heterocyclic carbene (NHC) boryl anion can be generated by reduction, and trapped electrophiles (see scheme; dipp=2,6-diisopropylphenyl) to provide new substituted NHC boranes. It is yet another example of a low-valent boron compound or boron-containing reactive intermediate stabilized an NHC, thereby extending the scope borane chemistry. Detailed facts importance specialist readers are published as ”Supporting Information”. Such documents...

A facile C-H activation and functionalization of aromatic imines is presented using low-valent cobalt catalysts. Using Co(PMe3)4 as catalyst we have developed an efficient simple protocol for the C-H/hydroarylation alkynes with anti selectivity. Deuterium-labeling experiments, DFT calculations coupled use a well-defined first time shed light on elusive black box catalyzed functionalization.

A well-defined copper complex bearing iminosemiquinone ligands performs single electron reduction of an electrophilic CF3+ source into CF˙3 radicals. This redox behavior is enabled by the ligand which shuttles through two different states (iminosemiquinone and iminobenzoquinone) while center preserved as a Cu(ii). system was used in trifluoromethylation silyl enol ethers, heteroaromatics hydrotrifluoromethylation alkynes. first example cooperative catalysis for controlled generation

QM/MM calculations are used to elucidate the Poulos−Kraut (Poulos, T. L.; Kraut, J. Biol. Chem. 1980, 255, 8199−8205) mechanism of O−O bond activation and Compound I (Cpd I) formation in HRP, conditions corresponding neutral basic pH. Attempts generate directly from Fe(H2O2) complex by migrating proton proximal oxygen distal one (1,2- shift) result high barriers. The lowest energy was found involve initial deprotonation ferric hydrogen peroxide (involving spin crossover quartet doublet...

We demonstrate by QM/MM calculations that the formation of Compound 0, an intermediate in catalytic cycle horseradish peroxidase, is catalyzed a single water molecule, which relays proton transfer between substrate (H2O2) and acceptor (His42). Thus, molecule enhances thermodynamic kinetic acidities H2O2 many orders magnitude. The behavior during activation may account for experimental reports extensive entropic effects principal active species enzyme I.

Expecting the unexpected: The title reaction leads to satisfactory yields of dihydrodibenzoazepines 1 a from norbornene. dibenzoazepines 2 can also be accessed compounds type b when norbornadiene is used as reactant. Theoretical studies show that represents chelation-driven deviation usual selectivity observed in presence ortho-substituents on aryl iodide. Detailed facts importance specialist readers are published "Supporting Information". Such documents peer-reviewed, but not copy-edited or...

We have investigated the dynamics of water molecules in distal pocket horseradish peroxidase to elucidate role that they may play formation principal active species enzymatic cycle (compound I, Por°+−FeIV═O) upon reaction resting FeIII state with hydrogen peroxide. The equilibrium molecular simulations show that, accord experimental evidence, site access channel is hydrated an average two three within 5 Å from bound Although always hydrated, specific conformations which a molecule bridges...

A method for the synthesis of phenanthridines from benzylamines and aryl iodides which uses a dual palladium-catalyzed process is developed. The domino sequence ends via an intramolecular amination oxidative dehydrogenation. No protecting group or prefunctionalization amine required, dioxygen as terminal oxidant.

Out of the norm: The first deviation from ortho effect in palladium/norbornene catalysis, as evidenced by resulting products, is reported (see scheme). DFT calculations indicate that this likely to originate a distortion, caused specific chelation, reductive-elimination pathway PdIV intermediate initially formed. Addition water restores normal selectivity, but also it leads dearomatization.

N-heterocyclic carbene-capped cyclodextrin (ICyD) ligands, α-ICyD and β-ICyD derived from α- β-cyclodextrin, respectively give opposite regioselectivities in a copper-catalyzed hydroboration. The site-selectivity results two different mechanisms: the conventional parallel one new orthogonal mechanism. shape of cavity was shown not only to induce regioselectivity switch but also mechanistic switch. scope interest encapsulation reactive center is therefore broadened by this study.

Abstract This works introduces hypervalent bis‐catecholato silicon compounds as versatile sources of alkyl radicals upon visible‐light photocatalysis. Using Ir[(dF(CF 3 )ppy) 2 (bpy)](PF 6 ) (dF(CF )ppy=2‐(2,4‐difluorophenyl)‐5‐trifluoromethylpyridine, bpy=bipyridine) catalytic photooxidant, a series radicals, including highly reactive primary ones can be generated and engaged in various intermolecular homolytic reactions. Based on cyclic voltammetry, Stern–Volmer studies, supported by...

Herein, the use of a well-defined low-valent cobalt(I) catalyst [HCo(PMe3)4] capable performing highly regio- and stereoselective hydrosilylation internal alkynes is reported. The reaction can be applied to variety hydrosilanes, symmetrical unsymmetrical alkynes, giving in many cases single isomer. Experimental theoretical studies suggest key step hydro-cobaltation that proceeds through classical Chalk-Harrod mechanism.

The development of new energy storage technologies is central to solving the challenges facing widespread use renewable energies.

Abstract The photophysical properties of a Keggin‐type polyoxometalate (POM) covalently bounded to benzospiropyran (BSPR) unit have been investigated. These studies reveal that both closed and open forms are emissive with distinct spectral features ( λ em (closed form)=530 nm, (open form)=670 nm) the fluorescence BSPR hybrid is considerably enhanced compared parent compounds. While excitation energy reference compounds (370 close intense absorption responsible photochromic character (350...

The encapsulation of copper inside a cyclodextrin capped with an N-heterocyclic carbene (ICyD) allowed both to catch the elusive monomeric (L)CuH and cavity-controlled chemoselective copper-catalyzed hydrosilylation α,β-unsaturated ketones. Remarkably, (α-ICyD)CuCl promoted 1,2-addition exclusively, while (β-ICyD)CuCl produced fully reduced product. chemoselectivity is controlled by size cavity weak interactions between substrate internal C-H bonds cyclodextrin.

We have determined the crystal structure of chloroperoxidase (CPO) hydroperoxo reaction intermediate (CPO compound 0) at 1.75-Å resolution. The was generated through controlled photoreduction CPO oxygen complex during x-ray data collection, which monitored by recording absorption spectra. Initially, peroxo-anion species formed and then protonated to yield 0. Quantum chemical calculations indicate that is not stable collapses instantaneously Compound 0 present in ferric low-spin doublet...

The organic side chain of tin-substituted Dawson polyoxotungstates alpha1- and alpha2-[P2W17O61{SnCH2CH2COOH}]7- can be used to direct regioselective acylations oxo ligands in the inorganic backbone, which was examined both experimentally computationally. Acylation ligand gave exalted electrophilicity acyl moiety, compounds that were obtained led ligation POMs complex molecules.

Niedervalente Borverbindung: Die im Titel genannte NHC-Bor-Verbindung wurde durch Reduktion erhalten und ließ sich Elektrophile unter Bildung neuer substituierter NHC-Borane abfangen (siehe Schema; dipp=2,6-Diisopropylphenyl). Entdeckung dieser ein NHC stabilisierten niedervalenten Borspezies erweitert die Bandbreite der NHC-Boran-Chemie. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset....

A convenient one-pot system has been developed, allowing the synthesis of highly substituted dihydropyridines via a C–H activation/6π-electrocyclization pathway. The reaction proceeds with high regioselectivity, and we disclose first example isolated lacking substitution in 2 position. Moreover, use simple well-defined low-valent cobalt complex without need for reducing agents or additives combination computational studies provides clearer insight into activation pathway than was previously reported.