Flexible Syntheses ofTripodal Phosphine Ligands 1,1,2-Tris(diarylphosphino)ethaneand Their Ruthenium η5-C5Me5 Complexes

Flexible Syntheses of
Tripodal Phosphine Ligands 1,1,2-Tris(diarylphosphino)ethane
and Their Ruthenium η5-C5Me5 Complexes:

Organometallics

DOI: 10.1021/om3005959

Metal-free Catalytic Olefin Hydrogenation: Low-Temperature H2 Activation by Frustrated Lewis Pairs

Metal-free Catalytic Olefin Hydrogenation: Low-Temperature H2 Activation by Frustrated Lewis Pairs:

Weak nucleophiles for strong activation: The reversible activation of dihydrogen by an electron-deficient phosphine, (C₆F₅)PPh₂, in combination with the Lewis acid B(C₆F₅)₃ at −80 °C was accomplished. The catalytic hydrogenation of olefins proceeds through protonation and subsequent hydride attack. Electron-deficient phosphines and diarlyamines were demonstrated to be viable Lewis bases for the reaction, thus allowing catalyst loadings of 10 to 5 mol %.

N,N-Dimethylformamide: A Multipurpose Building Block

N,N-Dimethylformamide: A Multipurpose Building Block:

Abstract

Often used as a common solvent for chemical reations and utilized widely in industry as a reagent, N,N-dimethylformamide (DMF) has played an important role in organic synthesis for a long time. Numerous highly useful articles and reviews discussing its utilizations have been published. With a focus on the performance of DMF as a multipurpose precursor for various units in numerous reactions, this Minireview summarizes recent developments in the employment of DMF in the fields of formylation, aminocarbonylation, amination, amidation, and cyanation, as well as its reaction with arynes.

All-purpose reagent: In addition to being an effective polar solvent for chemical reactions, N,N-dimethylformamide (DMF) can serve as the source for a variety of units, such as CHO, CHNMe₂, C(O)NMe₂, NMe₂, and CN among others (see scheme). Recent developments in the employment of DMF as a reactant are reviewed.

Construction of HeterometallicClusters in a SmallPeptide Scaffold as [NiFe]-Hydrogenase Models: Development of a SyntheticMethodology

Construction of Heterometallic
Clusters in a Small
Peptide Scaffold as [NiFe]-Hydrogenase Models: Development of a Synthetic
Methodology:

Inorganic Chemistry DOI: 10.1021/ic2026818

Solar Fuels: Visible-Light-Driven Generation of Dihydrogen at p-Type Silicon Electrocatalysed by Molybdenum Hydrides

Solar Fuels: Visible-Light-Driven Generation of Dihydrogen at p-Type Silicon Electrocatalysed by Molybdenum Hydrides:

Abstract

We show that a robust molybdenum hydride system can sustain photoelectrocatalysis of a hydrogen evolution reaction at boron-doped, hydrogen-terminated, p-type silicon. The photovoltage for the system is about 600–650 mV and the current densities, which can be sustained at the photocathode in non-catalytic and catalytic regimes, are similar to those at a photoinert vitreous carbon electrode. The kinetics of electrocatalysed hydrogen evolution at the photocathode are also very similar to those measured at vitreous carbon—evidently visible light does not significantly perturb the catalytic mechanism. Importantly, we show that the doped (1–10 Ω cm) p-type Si can function perfectly well in the dark as an ohmic conductor and this has allowed direct comparison of the cyclic voltammetric behaviour of the response of the system under dark and illuminated conditions at the same electrode. The p-type Si we have employed optimally harvests light energy in the 600–700 nm region and with 37 mW cm⁻² illumination in this range; the light to electrochemical energy conversion is estimated to be 2.8 %. The current yield of hydrogen under broad tungsten halide lamp illumination at 90 mW cm⁻² is (91±5) % with a corresponding chemical yield of (98±5) %.

In the light or dark with Moly at p-type Si: A molybdenum hydride/p-type Si system provides a stable platform for probing photoredox and photoelectrocatalytic behaviour. Whilst the kinetics of hydrogen evolution are slow, the Mo hydride catalyst offers options for considerable molecular tailoring. Cyclic voltammetry of an Mo electrocatalyst at the same p-type Si electrode in the dark (blue trace) and light (red trace) show a 640 mV photovoltage gain.

A Pyridinol Acyl Cofactor in the Active Site of [Fe]-hydrogenase Evidenced by the Reactivity of Model Complexes

A Pyridinol Acyl Cofactor in the Active Site of [Fe]-hydrogenase Evidenced by the Reactivity of Model Complexes:

Understanding the complex: The decomposition reaction of a water-soluble complex (see scheme; 1) in H₂O confirms the existence of a unique bidentate pyridinol cofactor in [Fe]-hydrogenase. This unique moiety is confirmed for the first time by the decomposition of a well-defined model complex containing a pyridinyl methyl acyl ligand.

Mechanistic Study of a One-Step Catalytic Conversion of Fructose to 2,5-Dimethyltetrahydrofuran

Mechanistic Study of a One-Step Catalytic Conversion of Fructose to 2,5-Dimethyltetrahydrofuran:

Abstract

Carbohydrates, such as fructose, can be fully dehydroxylated to 2,5-dimethyltetrahydrofuran (DMTHF), a valuable chemical and potential gasoline substitute, by the use of a dual catalytic system consisting of HI and RhX₃ (X=Cl, I). A mechanistic study has been carried out to understand the roles that both acid and metal play in the reaction. HI serves a two-fold purpose: HI acts as a dehydration agent (loss of 3 H₂O) in the initial step of the reaction, and as a reducing agent for the conjugated carbinol group in a subsequent step. I₂ is formed in the reduction step and metal-catalyzed hydrogenation reforms HI. The rhodium catalyst, in addition to catalyzing the reaction of iodine with hydrogen, functions as a hydrogenation catalyst for CO and CC bonds. A general mechanistic scheme for the overall reaction is proposed based on identification of intermediates, independent reactions of the intermediates, and deuterium labeling studies.

Sugar to fuel: Carbohydrates, such as fructose, can be fully dehydroxylated to 2,5-dimethyltetrahydrofuran (DMTHF), a valuable chemical and potential gasoline substitute, by the use of a dual catalytic system consisting of HI and RhX₃ (X=Cl, I; see scheme). A mechanistic study has been carried out to understand the roles that both acid and metal play in the reaction.

Evidence for Formationof a Co–H Bond from(H2O)2Co(dmgBF2)2 underH2: Application to Radical Cyclizations

Evidence for Formation
of a Co–H Bond from
(H2O)2Co(dmgBF2)2 under
H2: Application to Radical Cyclizations:

Journal of the American Chemical Society

DOI: 10.1021/ja306037w

Active Site Models forthe CuA Site ofPeptidylglycine α-Hydroxylating Monooxygenase and Dopamineβ-Monooxygenase

Active Site Models for the CuA Site of
Peptidylglycine α-Hydroxylating Monooxygenase and Dopamine
β-Monooxygenase:

Inorganic Chemistry DOI: 10.1021/ic301272h

Role of a Metal–MetalBonded Dimer Dication in the One-Electron Oxidation of Rh(η5-C5H5)(CO)(PPh3) and RelatedCompounds

Role of a Metal–Metal
Bonded Dimer Dication in the One-Electron Oxidation of Rh(η5-C5H5)(CO)(PPh3) and Related
Compounds:

Organometallics

DOI: 10.1021/om3003976

An Air-Stable Fe3S4 Complex with Properties Similar to Those of the HOXair State of the Diiron Hydrogenases

An Air-Stable Fe3S4 Complex with Properties Similar to Those of the HOXair State of the Diiron Hydrogenases:

Abstract

A Fe₃S₄ complex bridged by azapropanedithiolate (adt), complex 6, was prepared as a potential model of the H_OX^air state of [FeFe]-hydrogenases. Complex 6 was characterized by IR and ¹H NMR spectroscopy, and its structure was determined by X-ray crystallography. The electrochemical studies show that complex 6 is redox-active under acidic conditions, which provides insight into the catalytic mechanism. Hydrogen evolution, driven by visible light, was observed in CH₃CN/D₂O solution by online mass spectroscopy.

An air-stable Fe₃S₄ complex was prepared as a mimic of the H_OX^air state of the active site of [FeFe]-hydrogenases. Electrochemical and photoinduced hydrogen evolution is promoted by this catalyst.

Nickelation of PCP- andPOCOP-Type Pincer Ligands:Kinetics and Mechanism

Nickelation of PCP- and
POCOP-Type Pincer Ligands:
Kinetics and Mechanism:

Organometallics

DOI: 10.1021/om3003784

Electronic Structure ofan [FeFe] Hydrogenase ModelComplex in Solution Revealed by X-ray Absorption SpectroscopyUsing Narrow-Band Emission Detection

Electronic Structure of
an [FeFe] Hydrogenase Model
Complex in Solution Revealed by X-ray Absorption Spectroscopy
Using Narrow-Band Emission Detection:

Journal of the American Chemical Society

DOI: 10.1021/ja304970p

Ligand-Based Reductionof CO2 and Releaseof CO on Iron(II)

Ligand-Based Reduction
of CO2 and Release
of CO on Iron(II):

Inorganic Chemistry

DOI: 10.1021/ic3015404

An Air-Stable Fe3S4 Complex with Properties Similar to Those of the HOXair State of the Diiron Hydrogenases

An Air-Stable Fe3S4 Complex with Properties Similar to Those of the HOXair State of the Diiron Hydrogenases:

Abstract

A Fe₃S₄ complex bridged by azapropanedithiolate (adt), complex 6, was prepared as a potential model of the H_OX^air state of [FeFe]-hydrogenases. Complex 6 was characterized by IR and ¹H NMR spectroscopy, and its structure was determined by X-ray crystallography. The electrochemical studies show that complex 6 is redox-active under acidic conditions, which provides insight into the catalytic mechanism. Hydrogen evolution, driven by visible light, was observed in CH₃CN/D₂O solution by online mass spectroscopy.

An air-stable Fe₃S₄ complex was prepared as a mimic of the H_OX^air state of the active site of [FeFe]-hydrogenases. Electrochemical and photoinduced hydrogen evolution is promoted by this catalyst.

Organoselenium ligands in catalysis

Organoselenium ligands in catalysis:

Dalton Trans., 2012, Accepted Manuscript
DOI: 10.1039/C2DT31198D, Perspective

Ajai kumar Singh
Organoselenium ligands are building blocks of several transition metal complexes which catalyze various organic reactions readily as well as efficiently in solution. In this review the survey of developments pertaining...

Structural, Spectroscopic, and Electrochemical Properties of Nonheme Fe(II)-Hydroquinonate Complexes: Synthetic Models of Hydroquinone Dioxygenases

Structural, Spectroscopic, and Electrochemical Properties of Nonheme Fe(II)-Hydroquinonate Complexes: Synthetic Models of Hydroquinone Dioxygenases:

Dalton Trans., 2012, Accepted Manuscript
DOI: 10.1039/C2DT31504A, Paper

Amanda E. Baum, Heaweon Park, Denan Wang, Sergey Lindeman, Adam Thomas Fiedler

Mixed-Valence [FeIFeII] Hydrogenase Active Site Model Complexes Stabilized by a Bidentate Carborane bis-Phosphine Ligand

Mixed-Valence [FeIFeII] Hydrogenase Active Site Model Complexes Stabilized by a Bidentate Carborane bis-Phosphine Ligand:

Dalton Trans., 2012, Accepted Manuscript
DOI: 10.1039/C2DT31192E, Paper

Sascha Ott, Michael Karnahl, Stefanie Tschierlei, Ozlen Erdem, Sonja Pullen, Marie-Pierre Santoni, Edward Reijerse, Wolfgang Lubitz
A series of [FeFe]-hydrogenases active site analogues, with the general formula [Fe2(dt)(CO)4(BC)] 1-3 (dt = dithiolate, pdt = propyl- 1,3-dt (1), bdt = benzene-1,2-dt (2), edt = ethyl-1,2-dt (3); BC...
The content of this RSS Feed (c) The Royal Society of Chemistry

Carbon disulfide binding at dinuclear and mononuclear nickel complexes ligated by a redox-active ligand: Iminopyridine serving as an accumulator of redox equivalents for the activation of heteroallenes

Carbon disulfide binding at dinuclear and mononuclear nickel complexes ligated by a redox-active ligand: Iminopyridine serving as an accumulator of redox equivalents for the activation of heteroallenes:

Chem. Commun., 2012, Accepted Manuscript
DOI: 10.1039/C2CC34307J, Communication

Amarnath Bheemaraju, Jeffrey W. Beattie, Richard L. Lord, Philip D. Martin, Stanislav Groysman
The dinuclear complex Ni2L1([small eta]2-CS2)2 (2), featuring iminopyridine ligation, is prepared by COD substitutution from Ni2L1COD)2 (1). Spectroscopic, structural, and theoretical data reveals significant activation of the metal-bound C-S bonds, as...
The content of this RSS Feed (c) The Royal Society of Chemistry

Synthesis and Characterization of a (μ-η2:η2-Peroxido)dicopper(II) Complex with N,N′,N″-Triisopropyl-cis,cis-1,3,5-triaminocyclohexane (R3TACH, R = iPr): Selective Preparation of (μ-η2:η2-Peroxido)dicopper(II) and Bis(μ-oxido)dicopper(III) Species Regulated by Substituent Groups

Synthesis and Characterization of a (μ-η2:η2-Peroxido)dicopper(II) Complex with N,N′,N″-Triisopropyl-cis,cis-1,3,5-triaminocyclohexane (R3TACH, R = iPr): Selective Preparation of (μ-η2:η2-Peroxido)dicopper(II) and Bis(μ-oxido)dicopper(III) Species Regulated by Substituent Groups:

Abstract

The new Cu^I complex of N,N′,N″-triisopropyl-cis,cis-1,3,5-triaminocyclohexane (iPr₃TACH), [Cu(iPr₃TACH)(MeCN)](X), immediately reacts with dioxygen at –80 °C to give a (μ-η²:η²-peroxido)dicopper(II) complex. This observation is significantly different from the previously reported cases of bis(μ-oxido)dicopper(III) complexes that were generated by the reaction of copper(I) complexes of other TACH ligands (Et₃TACH, iBu₃TACH, and Bn₃TACH) with dioxygen under the same reaction conditions. Such selective preparations have been explained in terms of the structural specificity provided by the TACH ligands that surround the metal centers. The obtained (μ-η²:η²-peroxido)dicopper(II) complex exhibits ortho-hydroxylation of a phenolate to ortho-quinone with ca. 50 % yield based on the peroxido intermediate. The bis(μ-oxido)dicopper(III) complexes with other TACH derivatives are not capable of oxygenation of phenolate. The (μ-η²:η²-peroxido)dicopper core is discussed in the context of the reaction mechanism of tyrosinase.

The selective preparation of (μ-η²:η²-peroxido)dicopper(II) and bis(μ-oxido)dicopper(III) species is regulated by the substituent groups of triaminocyclohexane derivative ligands. Their structural and spectroscopic features and reactivity are discussed.

Dihydrogen Binding toIsostructural S = 1/2 and S = 0 Cobalt Complexes

Dihydrogen Binding to
Isostructural S = 1/2 and S = 0 Cobalt Complexes:

Journal of the American Chemical Society

DOI: 10.1021/ja305248f

Structural Control of 1A2u-to-3A2u IntersystemCrossing in Diplatinum(II,II) Complexes

Structural Control of 1A2u-to-3A2u Intersystem
Crossing in Diplatinum(II,II) Complexes:

Journal of the American Chemical Society

DOI: 10.1021/ja305666b

Photo-induced hydrogen production in a helical peptide incorporating a [FeFe] hydrogenase active site mimic

Photo-induced hydrogen production in a helical peptide incorporating a [FeFe] hydrogenase active site mimic:

Chem. Commun., 2012, Advance Article
DOI: 10.1039/C2CC34470J, Communication

Anindya Roy, Christopher Madden, Giovanna Ghirlanda
A new avenue to functional hydrogenase mimics by using an unnatural amino acid to incorporate a diiron hexacarbonyl cluster into peptides.
To cite this article before page numbers are assigned, use the DOI form of citation above.
The content of this RSS Feed (c) The Royal Society of Chemistry

Baeyer–Villiger Oxidation and Oxidative Cascade Reactions with Aqueous Hydrogen Peroxide Catalyzed by Lipophilic Li[B(C6F5)4] and Ca[B(C6F5)4]2

Baeyer–Villiger Oxidation and Oxidative Cascade Reactions with Aqueous Hydrogen Peroxide Catalyzed by Lipophilic Li[B(C6F5)4] and Ca[B(C6F5)4]2:

Efficient and selective: Two lipophilic catalysts were used for Baeyer–Villiger (BV) oxidations to give lactones in high yields (see scheme). Cascade reactions involving this BV oxidation were used to selectively obtain either unsaturated carboxylic acids or hydroxylactones in high yields from β-silyl cyclohexanones.

An instance of using Ca(BArF20)2.

Dihydrogen Binding toIsostructural S = 1/2 and S = 0 Cobalt Complexes

Dihydrogen Binding to
Isostructural S = 1/2 and S = 0 Cobalt Complexes:

Journal of the American Chemical Society

DOI: 10.1021/ja305248f

Mixed-Valence [FeIFeII] Hydrogenase Active Site Model Complexes Stabilized by a Bidentate Carborane bis-Phosphine Ligand

Mixed-Valence [FeIFeII] Hydrogenase Active Site Model Complexes Stabilized by a Bidentate Carborane bis-Phosphine Ligand:

Dalton Trans., 2012, Accepted Manuscript
DOI: 10.1039/C2DT31192E, Paper

Sascha Ott, Michael Karnahl, Stefanie Tschierlei, Ozlen Erdem, Sonja Pullen, Marie-Pierre Santoni, Edward Reijerse, Wolfgang Lubitz
A series of [FeFe]-hydrogenases active site analogues, with the general formula [Fe2(dt)(CO)4(BC)] 1-3 (dt = dithiolate, pdt = propyl- 1,3-dt (1), bdt = benzene-1,2-dt (2), edt = ethyl-1,2-dt (3); BC...
The content of this RSS Feed (c) The Royal Society of Chemistry

O2 Insertioninto Group 9 Metal–HydrideBonds: Evidence for Oxygen Activation through the Hydrogen-Atom-AbstractionMechanism

O2 Insertion
into Group 9 Metal–Hydride
Bonds: Evidence for Oxygen Activation through the Hydrogen-Atom-Abstraction
Mechanism:

Inorganic Chemistry

DOI: 10.1021/ic301303n

[Perspective] Chemistry: Uncovering the Uranium-Nitrogen Triple Bond

[Perspective] Chemistry: Uncovering the Uranium-Nitrogen Triple Bond: A triple bond formed between a high-valent uranium atom and a nitrogen atom has appreciable f orbital character.

Authors: Alfred P. Sattelberger, Marc J. A. Johnson

Synthesis, Reactivity, and Resolution of a C2–Symmetric, P–Stereogenic Benzodiphosphetane, a Building Block for Chiral Bis(phosphines)

Synthesis, Reactivity, and Resolution of a C2–Symmetric, P–Stereogenic Benzodiphosphetane, a Building Block for Chiral Bis(phosphines):

Organic Letters

DOI: 10.1021/ol301935q