899 research outputs found
A Terminal Chlorophosphinidene Complex
No full textTerminal, electrophilic phosphinidene complexes (M=PR) are attractive platforms for PR‐transfer to organic substrates. In contrast to aryl‐ or alkylphosphinidene complexes terminal chlorophosphinidenes (M=PCl) have only been proposed as transient intermediates but isolable example remain elusive. Here we present the transfer of PCl from chloro‐substituted dibenzo‐7λ3‐phosphanorbornadiene to a square‐planar osmium(II) PNP pincer complex to give the first isolable, terminal chlorophosphinidene complex with remarkable thermal stability. Os=P bonding was examined computationally giving rise to highly covalent {OsII=PICl} double bonding.image John Wiley \u0026 Sons, Ltd.European Research Council http://dx.doi.org/10.13039/50110000078
Combined experimental and theoretical studies towards mutual osmium–bismuth donor/acceptor bonding
No full textOsmium(II) PNP pincer complexes bearing a hemilabile pyridyl-pyrazolide (PyrPz) ligand have been synthesised, and their reactivity towards Lewis acidic bismuth compounds has been examined. Reactions with BiCl3 resulted in chlorine-atom-transfer to give an osmium(III) species. Reactions with cationic bismuth species led to adduct formation through N → Bi bond formation via the PyrPz ligand. Theoretical analyses revealed that steric interactions hamper Os → Bi bond formation and indicate that such interactions are possible upon reducing the steric profile around the osmium atom. Analytical techniques include NMR, IR, and EPR spectroscopy, cyclic voltammetry, elemental analysis and DFT calculations
) Anion as a Ligand
No full textThe utilization of monomeric, lower phosphorous oxides and oxoanions, such as metaphosphite (PO2−), which is the heavier homologue of the common nitrite anion but previously only observed in the gas phase and by matrix isolation, requires new synthetic strategies. Herein, a series of rhenium(I–III) complexes with PO2− as ligand is reported. Synthetic access was enabled by selective oxygenation of a terminal phosphide complex. Spectroscopic and computational examination revealed slightly stronger σ-donor and comparable π-acceptor properties of PO2− compared to homologous NO2−, which is one of the archetypal ligands in coordination chemistry
Coupling of terminal iridium nitrido complexes.
Full text linkThe oxidative coupling of nitride ligands (N3−) to dinitrogen and its microscopic reverse, N2-splitting to nitrides, are important elementary steps in chemical transformations, such as selective ammonia oxidation or nitrogen fixation. Here an experimental and computational evaluation is provided for the homo- and heterocoupling of our previously reported iridium(IV) and iridium(V) nitrides [IrN(PNP)]n (n = 0, +1; PNP = N(CHCHPtBu2)2). All three formal coupling products [(PNP)IrN2Ir(PNP)]n (n = 0–+2) were structurally characterized. While the three coupling reactions are all thermodynamically feasible, homocoupling of [IrN(PNP)]+ is kinetically hindered. The contributing parameters to relative coupling rates are discussed providing qualitative guidelines for the stability of electron rich transition metal nitrides
Metal-Ligand Cooperative Synthesis of Benzonitrile by Electrochemical Reduction and Photolytic Splitting of Dinitrogen
No full textThermal nitrogen fixation relies on strong reductants to overcome the extraordinarily large N−N bond energy. Photochemical strategies that drive N2 fixation are scarcely developed. Here, the synthesis of a dinuclear N2-bridged complex is presented upon reduction of a rhenium(III) pincer platform. Photochemical splitting into terminal nitride complexes is triggered by visible light. Clean nitrogen transfer with benzoyl chloride to free benzamide and benzonitrile is enabled by cooperative 2 H+/2 e− transfer of the pincer ligand. A three-step cycle is demonstrated for N2 to nitrile fixation that relies on electrochemical reduction, photochemical N2-splitting and thermal nitrogen transfer
Isolation of an Osmium(III) Hydrido Complex
No full textAbstract
Synthesis and characterization of [OsH(PNP)(bipy)]
+
(PNP=N(CHCHP
t
Bu
2
)
2
) are reported, as the second osmium(III) hydrido complex next to [OsH(en)
2
(py)]
2+
. While the osmium(II) precursor, [OsH(PNP)(bipy)], exhibits two reversible oxidations in the cyclic voltammogram, the product from 2‐electron oxidation could not be isolated due to rapid decay. Thermochemical examinations attribute the stability of the osmium(III) hydride to both thermodynamic and kinetic reasons. In contrast, the high estimated acidity of [OsH(PNP)(bipy)]
2+
presumably leads to rapid decay.Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659Fonds der Chemischen Industrie https://doi.org/10.13039/10001899
Envision Film Festival: Josh Larsen
No full textJosh Larsen, Radio Host, Author, Editor and Film Critic, Think Christian, Chicago, IL, speaks about the purpose and function of movies, and the possibility of seeing them as prayers.
This chapel preceded the Envision Film Festival
Four- and Five-Coordinate Osmium(IV) Nitrides and Imides: Circumventing the “Nitrido Wall”
No full textOsmium nitride chemistry is dominated by osmium(VI) in octahedral or square-pyramidal coordination. The stability of the d2 configuration and preference of the strong σ- and π-donor nitride for apical coordination is in line with the Gray–Ballhausen bonding model. In contrast, low-valent osmium(IV) or other d4 nitrides are rare and have only been reported with lower coordination numbers (CN ≤ 4), thereby avoiding π-bonding conflicts of the nitride ligand with the electron-rich metal center. We here report the synthesis of the square-planar osmium(IV) nitride [OsIVN(PNP)] (PNP = N(CHCHPtBu2)2). From there, a square-pyramidal isonitrile adduct could be isolated, which surprisingly features basal nitride coordination. Analysis of this five-coordinate d4 nitride shows an unusual binding mode of the isonitrile ligand, which explains the preference of the weakest σ-donor and strongest π-acceptor isonitrile for apical coordination
CCDC 2015020: Experimental Crystal Structure Determination
No full textRelated Article: Josh Abbenseth, Jean-Pierre H. Oudsen, Bas Venderbosch, Serhiy Demeshko, Markus Finger, Christian Herwig, Christian Würtele, Max C. Holthausen, Christian Limberg, Moniek Tromp, Sven Schneider|2020|Inorg.Chem.|59|14367|doi:10.1021/acs.inorgchem.0c0213
A square-planar osmium(<scp>ii</scp>) complex
No full textReduction of the pincer complex [OsIIICl2(PNP)] (PNP = N(CHCHPtBu2)2) affords the isolation and full characterization of an osmium(ii) complex with square-planar coordination geometry, i.e. [OsIICl(PNP)].</p
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