- Coordination and conformational isomers in mononuclear iron complexes with pertinence to the [FeFe] hydrogenase active site
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A series of six mononuclear iron complexes of the type [Fe(X-bdt)(P R2NPh2)(CO)] (PR 2NPh2 = 1,5-diaza-3,7-diphosphaoctane, bdt = benzenedithiolate with X = H, Cl2 or Me and R = Ph, Bn, Cyc or tert-Bu) was prepared. This new class of penta-coordinate iron complexes contains a free coordination site and a pendant base as essential structural features of the [FeFe]-hydrogenase active site. The bidentate nature of the PR2NPh2 ligands was found to be crucial for the preferential formation of coordinatively unsaturated penta-coordinate complexes, which is supported by first principle calculations. IR-spectroscopic data suggest the presence of coordination isomers around the metal center, as well as multiple possible conformers of the PR 2NPh2 ligand. This finding is further corroborated by X-ray crystallographic and computational studies. 31P{1H}-NMR- and IR-spectroscopic as well as electrochemical measurements show that the electronic properties of the complexes are strongly, and independently, influenced by the P-substituents at the PR2NPh2 ligand as well as by modifications of the bdt bridge. These results illustrate the advantages of this modular platform, which allows independent and selective tuning through site specific modifications. Potential catalytic intermediates, namely singly reduced and protonated complexes, have been further investigated by spectroscopic methods and exhibit remarkable stability. Finally, their general capacity for electro-catalytic reduction of protons to molecular hydrogen was verified.
- Orthaber, Andreas,Karnahl, Michael,Tschierlei, Stefanie,Streich, Daniel,Stein, Matthias,Ott, Sascha
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p. 4537 - 4549
(2014/03/21)
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- Water-soluble diphosphadiazacyclooctanes as ligands for aqueous organometallic catalysis
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Two new water-soluble diphosphacyclooctanes been synthesized and characterized by NMR and surface tension measurements. Both phosphanes proved to coordinate rhodium in a very selective way as well-defined bidentates were obtained. When used in Rh-catalyzed hydroformylation of terminal alkenes, both ligands positively impacted the reaction chemoselectivity.
- Boulanger, Jér?me,Bricout, Hervé,Tilloy, Sébastien,Fihri, Aziz,Len, Christophe,Hapiot, Frédéric,Monflier, Eric
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- Suzuki-Miyaura cross-coupling coupling reactions with low catalyst loading: A green and sustainable protocol in pure water
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The Suzuki-Miyaura coupling reaction represents one of the most important synthetic transformations developed in the 20th century. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance, and benign water as a reaction medium was found to be highly effective to overcome some of these issues. In the present manuscript, we described Suzuki-Miyaura coupling reactions in neat water, without using any phase transfer reagent. Notably, this protocol also works with ultra-low loading of catalyst with high turnover numbers and also able to couple challenging substrates like aryl chlorides.
- Fihri, Aziz,Luart, Denis,Len, Christophe,Solhy, Abderrahim,Chevrin, Carole,Polshettiwar, Vivek
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experimental part
p. 3116 - 3121
(2011/05/03)
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- Electrocatalytic oxidation of formate by [Ni(PR 2NR′2)2(CH3CN)] 2+ complexes
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[Ni(PR2NR′2) 2(CH3CN)]2+ complexes with R = Ph, R′ = 4-MeOPh or R = Cy, R′ = Ph, and a mixed-ligand [Ni(PR 2NR′2)(PR′′ 2NR′
- Galan, Brandon R.,Schoeffel, Julia,Linehan, John C.,Seu, Candace,Appel, Aaron M.,Roberts, John A. S.,Helm, Monte L.,Kilgore, Uriah J.,Yang, Jenny Y.,Dubois, Daniel L.,Kubiak, Clifford P.
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experimental part
p. 12767 - 12779
(2011/10/05)
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- Hydrogen oxidation catalysis by a nickel diphosphine complex with pendant tert-butyl amines
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A bis-diphosphine nickel complex with tert-butyl functionalized pendant amines [Ni(PCy2Nt-Bu2) 2]2+ has been synthesized. It is a highly active electrocatalyst for the oxidation of hydrogen
- Yang, Jenny Y.,Chen, Shentan,Dougherty, William G.,Kassel, W. Scott,Bullock, R. Morris,Dubois, Daniel L.,Raugei, Simone,Rousseau, Roger,Dupuis, Michel,Dubois, M. Rakowski
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supporting information; experimental part
p. 8618 - 8620
(2011/01/03)
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- Cyclohexylbis(hydroxymethyl)phosphane: A hydrophilic phosphane capable of forming novel hydrogen-bonding networks
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The cyclohexyl-substituted (hydroxymethyl)phosphane CyP-(CH 2OH)2 (1) has been prepared by reaction of the corresponding primary phosphane CyPH2 with aqueous formaldehyde. Compound 1 has been used as building block for the
- Gonschorowsky, Miriam,Merz, Klaus,Driess, Matthias
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p. 455 - 463
(2007/10/03)
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