Mechanistic Studies of Hydrogen Release from Solid Amine Borane Materials

2006 ◽  
Vol 927 ◽  
Author(s):  
Mark Bowden ◽  
Tim Kemmitt ◽  
Wendy Shaw ◽  
Nancy Hess ◽  
John Linehan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Kinetic Studies ◽  
Structural Data ◽  
Ammonia Borane ◽  
Hydrogen Release ◽  
Hydrogen Atoms ◽  
Reaction Proceeds ◽  
In Situ Nmr Spectroscopy ◽  
In Situ Nmr

ABSTRACTAmmonia borane (NH3BH3) is a molecular solid with a high volumetric and gravimetric density of hydrogen. We report room temperature structural data which shows how the freely rotating NH3 and BH3 groups allow a N-H…H-B dihydrogen bond in which hydrogen atoms on adjacent molecules are separated by only 1.90Å. The initial decomposition of ammonia borane at 80-100°C into (NH2BH2)n and H2 has been studied by in-situ nmr spectroscopy and kinetic studies using isotopic substitution. The reaction proceeds by a bimolecular pathway involving a [NH3BH2NH3]+BH4− intermediate with an activation energy of 136kJmol−1.

scholarly journals Mesoscopic simulations of the in situ NMR spectra of porous carbon based supercapacitors: Electronic structure and adsorbent reorganisation effects

2021 ◽  
Author(s):  
Anagha Sasikumar ◽  
Anouar Belhboub ◽  
Camille Bacon ◽  
Alexander C. Forse ◽  
John Griffin ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Nmr Spectroscopy ◽  
Molecular Species ◽  
Porous Carbon ◽  
Nmr Spectra ◽  
Charge Storage ◽  
In Situ Nmr Spectroscopy ◽  
In Situ Nmr ◽  
Carbon Based

In situ NMR spectroscopy is a powerful technique to investigate charge storage mechanisms in carbon-based supercapacitors thanks to its ability to distinguish ionic and molecular species adsorbed in the porous...

Alkene Difunctionalization Directed by Free Amines: Diamine Synthesis via Nickel-Catalyzed 1,2-Carboamination

2021 ◽  
Author(s):  
Taeho Kang ◽  
José Manuel González ◽  
Zi-Qi Li ◽  
Klement Foo ◽  
Peter Cheng ◽  
...  
Keyword(s):  
Nickel Catalyst ◽  
Room Temperature ◽  
Kinetic Studies ◽  
Fine Tuning ◽  
Secondary Amines ◽  
Protecting Group ◽  
Wide Range ◽  
Leaving Group ◽  
Primary And Secondary Amines ◽  
Reaction Proceeds

A versatile method to access differentially substituted 1,3- and 1,4-diamines via a nickel-catalyzed three-component 1,2-carboamination of alkenyl amines with aryl/alkenylboronic ester nucleophiles and N–O electrophiles is reported. The reaction proceeds efficiently with free primary and secondary amines without needing a directing auxiliary or protecting group, and is enabled by fine-tuning the leaving group on the N–O reagent. The transformation is highly regioselective and compatible with a wide range of coupling partners and alkenyl amine substrates, all performed at room temperature. A series of kinetic studies support a mechanism in which alkene coordination to the nickel catalyst is turnover-limiting.

scholarly journals Non-Selective Dimerization of Vinyl Silanes by the Putative (Phenanthroline)PdMe Cation to 1,4-Bis(trialkoxysilyl)butenes

Inorganics ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 102
Author(s):  
Sandun Perera ◽  
Michael Findlater
Keyword(s):  
Nmr Spectroscopy ◽  
Palladium Complex ◽  
Organic Products ◽  
Vinyl Silanes ◽  
In Situ Nmr Spectroscopy ◽  
In Situ Nmr ◽  
Moderate Yield

Activation of the dialkylpalladium complex (phen)Pd(CH3)2 (phen = 1,10-phenanthroline) with B(C6F5)3 affords a competent catalyst for the dimerization of vinyl silanes. All organic products of the catalytic dimerization of trialkoxyvinylsilanes were characterized by in situ NMR spectroscopy and GC–MS. The putative palladium cation was characterized by NMR spectroscopy. Upon activation, the palladium complex generated products in moderate yield (60–70%) and selectivity (~60:40, dimer:disproportionation products).

scholarly journals Investigating the effect of a fluoroethylene carbonate additive on lithium deposition and the solid electrolyte interphase in lithium metal batteries using in situ NMR spectroscopy

2020 ◽  
Vol 8 (30) ◽  
pp. 14975-14992 ◽  
Author(s):  
Anna B. Gunnarsdóttir ◽  
Sundeep Vema ◽  
Svetlana Menkin ◽  
Lauren E. Marbella ◽  
Clare P. Grey
Keyword(s):  
Formation Rate ◽  
Solid Electrolyte Interphase ◽  
Lithium Metal Batteries ◽  
Nmr Study ◽  
Fluoroethylene Carbonate ◽  
Fast Transport ◽  
Fluoroethylene Carbonate Additive ◽  
In Situ Nmr Spectroscopy ◽  
In Situ Nmr

An in situ NMR study of Li deposition and the SEI on Li metal. Isotope exchange measurements reveal the fast transport properties in the SEI formed with FEC and the accelerated SEI formation rate, in part explaining the homogeneous electrodeposition using FEC additives.

scholarly journals Selective Nitration of Chlorobenzene by NO2 in the Alkali Zeolite NaZSM-5

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Scott J. Kirkby
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Temperature Dependent ◽  
Reaction Conditions ◽  
Cation Site ◽  
Zeolite Lattice ◽  
Reaction Proceeds ◽  
Ft Ir ◽  
Electron Donation

Chlorobenzene was reacted with NO2, in the initially acid-free zeolite NaZSM-5, to yield para-chloronitrobenzene exclusively. The precursors were loaded sequentially into self-supporting pellets of the zeolite, contained within a stainless steel cell, from the gas phase. The reaction proceeds spontaneously at room temperature. It is, however, very temperature dependent and effectively ceases at zero degrees Celsius. The reaction was monitored in situ using FT-IR. The active nitrating agent is formed from the partial electron donation by the NO2 to the Na+ cations present in the zeolite lattice. Under the reaction conditions, chlorobenzene is not readily mobile through the pore system; thus, only the molecules adsorbed near a cation site react to form para-chloronitrobenzene.

Interactions in ionic liquids probed by in situ NMR spectroscopy

2014 ◽  
Vol 192 ◽  
pp. 55-58 ◽  
Author(s):  
Ralf Giernoth ◽  
Andreas Bröhl ◽  
Martin Brehm ◽  
Yves Lingscheid
Keyword(s):  
Ionic Liquids ◽  
Nmr Spectroscopy ◽  
In Situ Nmr Spectroscopy ◽  
In Situ Nmr
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