Search results for "Hydride"

Toward an understanding of the hydrogenation reaction of MO2 gas-phase clusters (M = Ti, Zr, and Hf).

2013

A theoretical investigation using density functional theory (DFT) has been carried out in order to understand the molecular mechanism of dihydrogen activation by means of transition metal dioxides MO2 (M = Ti, Zr, and Hf) according to the following reaction: MO2 + H2 → MO + H2O. B3LYP/6-311++G(2df,2pd)/SDD methodology was employed considering two possible reaction pathways. As the first step hydrogen activation by M═O bonds yields to metal-oxo hydride intermediates O═MH(OH). This process is spontaneous for all metal dioxides, and the stability of the O═MH(OH) species depends on the transition metal center. Subsequently, the reaction mechanism splits into two paths: the first one takes place…

Pd/C-Catalyzed Hydrosilylation of Enals and Enones with Triethylsilane: Conformer Populations Control the Stereoselectivity

2016

The palladium-on-charcoal-catalyzed chemo-, regio-, and stereoselective 1,4-hydrosilylation and transfer hydrogenation reactions of α,β-unsaturated aldehydes and ketones with triethylsilane have been investigated with a combination of experimental and theoretical methods. The reaction mechanism has been studied experimentally by monitoring the reactions by 1H NMR from aliquots withdrawn from the stirred reaction mixtures, labeling experiments, and control experiments. Our density functional theory results indicate that both aforementioned reactions are initiated with a dissociative adsorption of the triethylsilane on the palladium catalyst. In the hydrosilylation reaction, the α,β-unsaturat…

Chain-extending of Hydroxytelechelic Polybutadiene: Synthesis and Characterization

2010

Extension of hydroxytelechelic polybutadiene oligomers ( 3200 g/mol) is performed in mild conditions, in order to avoid backbone modifications, using succinic anhydride or methylenedicyclohexyl diisocyanate. The two routes present significative extension of the initial oligomers. Extension through the anhydride route, in the presence of DCC and DMAP, leads to new hydroxytelechelic oligomers ( 8000 g/mol). Extension through the diisocyanate route, catalyzed by DBTL at 65°C leads to hydroxytelechelic oligomers of higher average molecular weight ( 20000 g/mol). New materials are characterized by FTIR/1H-NMR and changes in their Tg according to , are discussed. The influence of reaction time on…

CuCl catalyzed radical cyclisation of N-alpha-perchloroacyl-ketene-N,S-acetals: a new way to prepare disubstituted maleic anhydrides

2012

The discovery that cycloalkanes can form thermomorphic systems with typical polar organic solvents has led to the development of less-polar electrolyte solutions. Their mixing and separation can be regulated reversibly at a moderate temperature range. The phase switching temperature can be controlled by changing the solvent compositions. While biphasic conditions are maintained below the phase switching temperature, conductive monophasic conditions as less-polar electrolyte solutions are obtained above the phase switching temperature. After the electrochemical transformations, biphasic conditions are reconstructed below the phase switching temperature, facilitating the separation of cycloal…

Nanostructuring - a possible way to enhance the hydrogen sorption properties of materials

2009

Role of SH-Groups and S-S Bridges in the Main Subunit (1/12 Molecule) of Spirographis Spallanzanii Chlorocruorin

1986

In all species of annelids described, the extracellular hemoglobins show (by electron microscopy) the same quaternary structure constituted by twelve identical subunits. The fine structure of the 1/12 subunit is not well resolved and several models have been proposed for it (2).

Fluorine laser-induced silicon hydride SiH groups in silica

2007

Abstract Formation and destruction of silicon hydride (Si–H) groups in silica by F 2 laser irradiation and their vacuum ultraviolet (VUV) optical absorption was examined by infrared (IR) and VUV spectroscopy. Photoinduced creation of Si–H groups in H 2 -impregnated oxygen deficient silica is accompanied by a growth of infrared absorption band at 2250 cm −1 and by a strong increase of VUV transmission at 7.9 eV. Photolysis of Si–H groups by 7.9 eV photons in this glass was not detected when the irradiation was performed at temperature 80 K. However, a slight destruction of Si–H groups under 7.9 eV irradiation was observed at the room temperature. This finding gives a tentative estimate of VU…

Die spontane Desaktivierung beim oligomeren α-Methylstyryl-Natrium in Tetrahydrofuran

1972

Bei der Alterung von oligomerem α-Methylstyryl-Na in Tetrahydrofuran (THF) erfolgt eine Hydridabspaltung an der aktiven Endgruppe und ein Protonentransfer vom Losungsmittel. Der Selbstabbruch kann durch ein einfaches Schema von Simultanreaktionen beschrieben werden. Aging of α-methylstyryl-sodium oligomers in tetrahydrofuran (THF) results in the splitting-off of hydride at the active endgroup and in a protontransfer from the solvent. The mechanism of the self-termination can be described by a simple scheme of simultaneous reactions.

CCDC 769441: Experimental Crystal Structure Determination

2011

Related Article: D.Siebler, C.Forster, K.Heinze|2010|Eur.J.Inorg.Chem.||3986|doi:10.1002/ejic.201000384

CCDC 1508075: Experimental Crystal Structure Determination

2016

Related Article: Christopher G. Gianopoulos, Bartosz Zarychta, Simone Cenedese, Vladimir V. Zhurov, A. Alan Pinkerton|2016|J.Phys.Chem.A|120|4059|doi:10.1021/acs.jpca.6b03787