Thursday, December 27, 2012

Influence of the diamine on the reactivity of thiosulfonato ruthenium complexes with hydrosulfide (HS-)


Dalton Trans., 2013, Advance Article
DOI: 10.1039/C2DT31758C, Paper
Erwan Galardon, Hombeline Daguet, Patrick Deschamps, Pascal Roussel, Alain Tomas, Isabelle Artaud
The reaction of thiosulfonato ruthenium complexes [(p-cymene)Ru(bipy)(SSO2Ar)]+ with the hydrosulfide anion SH- is governed by the nature of the diamine.

Asymmetric Hydrogenation Using Rhodium Complexes Generated from Mixtures of Monodentate Neutral and Anionic Phosphorus Ligands

A series of monodentate neutral and anionic phosphorus ligands was synthesized and evaluated in the asymmetric rhodium-catalyzed hydrogenation of functionalized olefins by using either catalysts containing identical ligands or catalysts generated from mixtures of two different ligands. We expected that the combination of an anionic ligand with a neutral ligand would favor the formation of hetero over homo bis-ligand complexes due to charge repulsion. NMR spectroscopic studies confirmed that charge effects can indeed shift the equilibrium toward the hetero bis-ligand complexes. In several cases, the combination of a neutral phosphane with an anionic phosphane, one chiral and the other achiral, furnished significantly higher enantioselectivities than analogous mixtures of two neutral ligands. The best results were obtained with a mixture of an anionic phosphoramidite and a neutral phosphoric acid diester. It is supposed that in this case a hydrogen bond between the two ligands additionally stabilizes the hetero ligand combination.
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Charge effects and hydrogen bonding favor the formation of rhodium hetero bis-ligand complexes from mixtures of neutral and anionic monodentate phosphorus ligands. The combination of a neutral phosphoric acid diester as a hydrogen donor and an anionic phosphoramidite as a hydrogen acceptor gives very high enantioselectivities in Rh-catalyzed hydrogenation reactions, thus exceeding the enantiomeric excesses of the corresponding homo bis-ligand complexes (see scheme).

Contrasting ProtonationBehavior of Diphosphido vsDithiolato Diiron(I) Carbonyl Complexes

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Organometallics
DOI: 10.1021/om300997s

Wednesday, December 26, 2012

Robust Photogeneration of H2 in Water Using Semiconductor Nanocrystals and a Nickel Catalyst

A photoreduction system combining nanoparticulate light absorbers with a soluble molecular catalyst proves stable for weeks.

Authors: Zhiji Han, Fen Qiu, Richard Eisenberg, Patrick L. Holland, Todd D. Krauss

Iridium and Rhodium Complexes with the Hemilabile Ligand [2-(1,3-Dioxolane-2-yl)phenyl]diphenylphosphane – Behaviour in Solution and Structural Characterization

[MCl(L2)]2 (M = Ir, L2 = 1,5-cyclooctadiene; M = Rh, L2 = norbornadiene) reacts with [2-(1,3-dioxolane-2-yl)phenyl]diphenylphosphane (1) to afford [MCl(L2)(P~O)] (M = Ir, 2; M = Rh, 3), in which the ligand is P-monodentate. Complex 3 reacts with AgClO4 to give [Rh(Nbd)(PO)]ClO4 (4), in which the ligand is P,O-bidentate. Complex 2 is static at room temp., whereas 3 and 4 undergo intramolecular exchanges, which are fast at room temperature and slow at 223 K. The conformational changes in 4 are still fast at 223 K. Complexes 24 react with CO to afford trans-[MCl(CO)(P~O)2] (M = Ir, 5; M = Rh, 6) or trans-[Rh(CO)2(P~O)2]ClO4 (7). Cyclooctadiene complexes react with PPh2(o-C6H4CHO) to afford [MClH(PPh2(o-C6H4CO))(PO] (M = Ir, 8; M = Rh, 9), in which 1 is chelating. Complex 8 contains a single diastereomer, is static in the 303–213 K range and reacts with CO to form [IrClH(PPh2(o-C6H4CO))(P~O)(CO)] (10). Complex 9 contains two diastereomers 9a/9b in a 95:5 ratio that undergo interconversion, which is slow at low temperature, and reacts with CO to undergo reductive elimination of aldehyde, cleavage of the Rh–O bond and scrambling of phosphanes. A mixture of trans-[RhCl(CO)(κ1-PPh2(o-C6H4CHO))(P~O)] (11), 6 and trans-[RhCl(CO)(κ1-PPh2(o-C6H4CHO))2] is formed. Bubbling of nitrogen transforms 11 back into 9. Compound 2 reacts with hydrogen to give the fluxional [IrCl(H)2(P~O)(PO)] (12) with trans P atoms and cis H atoms, which attains coalescence at 203 K. Complex 12 reacts with mono- or bidentate ligands to afford static [IrCl(H)2(P~O)2L] (L = CO, 13; py, 14; nPrNH2, 15) or [Ir(H)2(P~O)2(en)]BPh4 (16, en = ethylenediamine). Abstraction of halide from 12 affords [Ir(H)2(PO)2]BPh4 (17), which is fluxional owing to interconversion between only two of the possible four diastereomers, for which ΔH = 54.7 ± 0.7 kJ mol–1 and ΔS = 4.7 ± 0.2 J K–1 mol–1. The X-ray structures of 8, 15 and 16 are also reported.
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[2-(1,3-Dioxolane-2-yl)phenyl]diphenylphosphane (1) coordinates to MI preferably as a κ1-P ligand. MIII may afford κ2-P,O coordination in dynamic diastereomers such as A or B. A contains a single diastereomer if M = Ir or two diastereomers in a 95:5 ratio if M = Rh. B contains a mixture of only two diastereomers.

Selective Redox Activationof H2 or O2 in a [NiRu] Complex by AromaticLigand Effects

Ogo
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Organometallics
DOI: 10.1021/om300833m

Synthesis, Structure,and Reactivity of Iridium(III)Complexes Containing a 4,6-Dimethyl-1,3-benzenediphenylimine PincerLigand

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Inorganic Chemistry
DOI: 10.1021/ic302589b

Novel diiminopyridine

Oxidation and Reductionof Bis(imino)pyridine Iron Dinitrogen Complexes: Evidence for Formationof a Chelate Trianion.


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Inorganic Chemistry
DOI: 10.1021/ic301675t

Copper-, Palladium-,and Platinum-Containing Complexes of an Asymmetric Dinucleating Ligand

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Inorganic Chemistry DOI: 10.1021/ic301914u

Iron Sulfide CatalyzedRedox/Condensation CascadeReaction between 2-Amino/Hydroxy Nitrobenzenes and ActivatedMethyl Groups: A Straightforward Atom Economical Approach to 2-Hetaryl-benzimidazolesand -benzoxazoles

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Journal of the American Chemical Society DOI: 10.1021/ja311780a

Friday, December 21, 2012

Characterization of a Macrocyclic end-on Peroxido Copper Complex

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Thirty years on: The dinuclear copper peroxido complex [(tet b)CuO2Cu(tet b)]2+ has been structurally characterized (see picture: Cu yellow, O red, N pink; tet b=rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). This complex is quite persistent in solution at room temperature and is the first example of a structurally characterized copper dioxygen adduct complex with a macrocyclic ligand based on earlier studies by Valentine et al.

NMR in Organometallic Chemistry. By Paul S. Pregosin.

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Wiley-VCH, Weinheim, 2012. 392 pp., softcover, € 59.00.—ISBN 978-3527330133

need this book, probably will be ebook via library - spread the word

Simplifying Iron–Phosphine Catalysts for Cross-Coupling Reactions

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Any old iron? Iron catalysts based on the widely available diphosphine ligand bis(diphenylphosphino)ethane have not previously fared particularly well in iron-catalyzed cross-coupling processes. However, this turns out not to be due to any inherently poor performance associated with the ligand, but rather the need to form a bis-chelate complex, either before or during the formation of an active FeI species.

Biomimetic model for [FeFe]-hydrogenase: Asymmetrically disubstituted diiron complex with a redox-active 2,2'-bipyridyl ligand


Dalton Trans DOI: 10.1039/C2DT32457A, Paper
Souvik Roy, Thomas L Groy, Anne Katherine Jones
[FeFe]-hydrogenases feature a unique active site in which the primary catalytic unit is directly coordinated via a bridging cysteine thiolate to a secondary, redox active [4Fe4S] unit. The goal of...

Not very interesting but she does propose that bipy is non-innocent

Thursday, December 20, 2012

Redox active aluminium(III) complexes convert CO2 into MgCO3 or CaCO3 in a synthetic cycle using Mg or Ca metal


Chem. Commun., 2013, Advance Article
DOI: 10.1039/C2CC37208H, Communication
Thomas W. Myers, Louise A. Berben
Using concomitant redox and acid-base reactivity, conversion of CO2 into MgCO3 or CaCO3, via regenerable (IP-)2Al(OH), is presented (IP = [small alpha]-iminopyridine).

Bioinspired catalytic nitrile hydration by dithiolato, sulfinato/thiolato, and sulfenato/sulfinato ruthenium complexes

Bioinspired catalytic nitrile hydration by dithiolato, sulfinato/thiolato, and sulfenato/sulfinato ruthenium complexes:
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C2CC35256G, Communication
Davinder Kumar, Cesar A. Masitas, Tho N. Nguyen, Craig A. Grapperhaus
Sulfur-oxidation of nitrile hydratase inspired Ru(II) catalysts enhances hydration activity and reduces product inhibition.
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Four-electron reduction of dioxygen catalysed by dinuclear cobalt complexes bridged by bis(terpyridyl)anthracene

Four-electron reduction of dioxygen catalysed by dinuclear cobalt complexes bridged by bis(terpyridyl)anthracene:
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C2CC36528F, Communication
Tohru Wada, Hidetaka Maki, Tomoyuki Imamoto, Hirokazu Yuki, Yuji Miyazato
We have prepared dinuclear cobalt complexes 1 and 2 linked in a co-facial configuration by bis(terpyridyl)anthracene as catalysts for chemical and electrochemical four-electron reductions of dioxygen.
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A photoactive basket-like metal-organic tetragon worked as an enzymatic molecular flask for light driven H2 production

A photoactive basket-like metal-organic tetragon worked as an enzymatic molecular flask for light driven H2 production:
Chem. Commun., 2013, 49,627-629
DOI: 10.1039/C2CC37853A, Communication
Cheng He, Jian Wang, Liang Zhao, Tao Liu, Jing Zhang, Chunying Duan
A photoactive basket-like metal-organic tetragon containing a carbazole photosensitizer was developed to capture the [FeFe]-H2ases for light driven H2 production.
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A stable and strongly luminescent dinuclear Cu(I) helical complex prepared from 2-diphenylphosphino-6-methylpyridine

A stable and strongly luminescent dinuclear Cu(I) helical complex prepared from 2-diphenylphosphino-6-methylpyridine:
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C2CC37873F, Communication
Juan-Jose Cid, John Mohanraj, Meera Mohankumar, Michel Holler, Gianluca Accorsi, Lydia Brelot, Iwona Nierengarten, Omar Moudam, Adrien Kaeser, Beatrice Delavaux-Nicot, Nicola Armaroli, Jean-Francois Nierengarten
[Cu2([small mu ]-dpPyMe)3(CH3CN)](BF4)2 exhibits a strong blue-greenish emission in the solid state.
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A highly sensitive and selective turn-on fluorescent chemosensor for palladium based on a phosphine-rhodamine conjugate


Chem. Commun., 2013, Advance Article
DOI: 10.1039/C2CC37746B
Songtao Cai, Yan Lu, Song He, Fangfang Wei, Liancheng Zhao, Xianshun Zeng
A fluorescent chemosensor for palladium species based on a conjugate of phosphine and rhodamine B shows an excellent palladium selectivity with a detection limit down to the 10-9 M range.

Wednesday, December 19, 2012

Molecular engineering of a cobalt-based electrocatalytic nanomaterial for H2 evolution under fully aqueous conditions

Molecular engineering of a cobalt-based electrocatalytic nanomaterial for H2 evolution under fully aqueous conditions:

Nature Chemistry 5, 48 (2013).
doi:10.1038/nchem.1481

Authors: Eugen S. Andreiadis, Pierre-André Jacques, Phong D. Tran, Adeline Leyris, Murielle Chavarot-Kerlidou, Bruno Jousselme, Muriel Matheron, Jacques Pécaut, Serge Palacin, Marc Fontecave & Vincent Artero
Efficient hydrogen-evolving catalysts comprising readily available elements are needed if hydrogen is to be adopted as a clean alternative to fossil fuels. Now, a diimine–dioxime cobalt complex has been covalently attached to a carbon nanotube electrode to yield an active and robust electrocatalyst for hydrogen generation (55,000 turnovers in seven hours) from aqueous solutions.