Mechanistic Study of Metal–Ligand Cooperativity in Mn(II)-Catalyzed Hydroborations: Hemilabile SNS Ligand Enables Metal Hydride-Free Reaction Pathway

A remarkable finding of metal hydride hydrogen storage is that substituting 4 mol % sodium by potassium in 4 mol % Ti-doped NaAlH4 raises the reversible hydrogen storage capacity from 3.3 % w/w H to 4.7 % w/w H. This increase by 42% is concomitant with a slightly lower desorption enthalpy: intriguingly enough, it is substantially more hydrogen capacity at slightly less desorption enthalpy. The general solution to that puzzle has been already derived from a gas phase point of view, taking advantage of the equilibrium nature of the matter, which thus comes in terms of an ideal gas chemical potential. However, it is also interesting to investigate for the flipside effect in the sorbent phase, affecting molar volume. This paper elucidates by the example of K/Ti-co-doped NaAlH4 the relation of doping modifications to surplus hydrogen amount and hydride molar volume, defining the term “reaction pathway” in this context, yielding the according figures.

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Determination of metal-hydride and metal-ligand (L = CO, N2) bond energies using photoacoustic calorimetry

Journal of the American Chemical Society ◽

10.1021/ja00058a043 ◽

1993 ◽

Vol 115 (5) ◽

pp. 1921-1925 ◽

Cited By ~ 10

Author(s):

Simon T. Belt ◽

J. C. Scaiano ◽

Michael K. Whittlesey

Keyword(s):

Metal Hydride ◽

Bond Energies ◽

Photoacoustic Calorimetry ◽

Metal Ligand

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How bulky ligands control the chemoselectivity of Pd-catalyzed N-arylation of ammonia

Chemical Science ◽

10.1039/c9sc03095f ◽

2020 ◽

Vol 11 (4) ◽

pp. 1017-1025 ◽

Cited By ~ 3

Author(s):

Seoung-Tae Kim ◽

Suyeon Kim ◽

Mu-Hyun Baik

Keyword(s):

Design Principle ◽

Steric Effect ◽

Reaction Pathway ◽

Mechanistic Study ◽

Bulky Ligands

Steric bulk has been recognized as a central design principle for ligands in the widely utilized Buchwald–Hartwig amination. This mechanistic study reveals how this steric effect manipulates the reaction pathway and determines the chemoselectivity.

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The Key to the Problem of Reversible Chemical Hydrogen Storage is 12 kJ (mol H2)-1

10.26434/chemrxiv.6940379.v4 ◽

2019 ◽

Author(s):

Roland Hermann Pawelke

Keyword(s):

Hydrogen Storage ◽

Specific Energy ◽

Metal Hydride ◽

Storage Capacity ◽

Reaction Pathway ◽

Worked Examples ◽

Ideal Gas ◽

Hydrogen Electrode ◽

Battery Cell ◽

General Applicability

This article outlines a simple theoretical formalism illuminating the boundaries to reversible solid hydrogen storage, based on the ideal gas law and classic equilibrium thermodynamics. A global picture of chemical reversible hydrogen sorption is unveiled, including a thermodynamic explanation of partial reversibility. The general applicability to experimental reality is demonstrated with pinpoint-accuracy by means of worked examples from metal hydride chemistry and electrochemistry (see ESI). Highlights of the metal hydride cases are why the substitution of 4 mol % Na by K in Ti-doped sodium alanate raises the reversible storage capacity from 3.3 to 4.7 % w/w H and the outlining of the additional reaction pathway in Mg(NH2)2/2LiH when doped with (Rb/K)H, increasing the reversible storage capacity from 3.6 to 4.4 % w/w H. The electrochemical case study derives the theoretical specific energy threshold for Li-batteries (274 Ah kg-1) from the standard hydrogen electrode potential and then figures for a practical example the reversible specific energy (a T5 NAS-battery cell by NGK Insulators Ltd.).

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Cyanide-Mediated Synthesis of Sulfones and Sulfonamides from Vinyl Sulfones

Synlett ◽

10.1055/s-0039-1690991 ◽

2019 ◽

Vol 31 (05) ◽

pp. 455-458

Author(s):

Tamal Roy ◽

Ji-Woong Lee

Keyword(s):

High Selectivity ◽

Reaction Pathway ◽

Secondary Amines ◽

Mechanistic Study ◽

Facile Synthesis ◽

Primary And Secondary Amines ◽

In Situ Generation ◽

High Yields

We report a facile synthesis of sulfones, β-keto sulfones, and sulfonamides from vinyl sulfones via an addition–elimination sequence where in situ generation of nucleophilic sulfinate ion is mediated by cyanide. The use vinyl sulfones renders high selectivity for S-alkylation to produce sulfones in high yields. In the presence of N-bromosuccinimide, primary and secondary amines underwent sulfonamide formation. A preliminary mechanistic study showed the formation of acrylonitrile as an innocent byproduct, without interfering with the desired reaction pathway while generating a sulfinate nucleophile.

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New reduction mechanism of CO dimer by hydrogenation to C2H4 on a Cu(100) surface: theoretical insight into the kinetics of the elementary steps

RSC Advances ◽

10.1039/c5ra15905a ◽

2015 ◽

Vol 5 (117) ◽

pp. 96281-96289 ◽

Cited By ~ 11

Author(s):

Lihui Ou ◽

Wenqi Long ◽

Yuandao Chen ◽

Junling Jin

Keyword(s):

Reaction Pathway ◽

Mechanistic Study ◽

Reduction Mechanism ◽

Elementary Steps ◽

Kinetics Of ◽

Theoretical Insight ◽

Insight Into

An alternative reaction pathway for the production of C2H4 through the OCCO* intermediate from CO dimerization is provided in this mechanistic study.

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MECHANISTIC STUDY OF THE REACTIONS OF SULFUR TRIOXIDE WITH HYDROGEN HALIDES TO FORM SUPERACID AND SURVEY OF HALO-SULFONIC ACID STRENGTH

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633605001696 ◽

2005 ◽

Vol 04 (spec01) ◽

pp. 623-638 ◽

Cited By ~ 4

Author(s):

KEVIN H. WEBER ◽

JULIE A. HARRIS ◽

LAURA J. LARSON ◽

FU-MING TAO ◽

SHUJIN LI ◽

...

Keyword(s):

Sulfonic Acid ◽

Sulfur Trioxide ◽

Density Functional ◽

Reaction Pathway ◽

Mechanistic Study ◽

Functional Theory ◽

Hydrogen Halides ◽

Donor Acceptor ◽

Hydrolysis Of ◽

Equilibrium Geometries

The reaction mechanisms for the formations of halo-sulfonic acids from sulfur trioxide and hydrogen halides are investigated using density functional theory. Two channels of reaction are considered: the binary SO 3 + HX reaction pathway and the ternary SO 3 + 2 HX pathway. Equilibrium geometries, harmonic frequencies, and relative energies of the reactant, transition state, and product clusters are calculated at the B3LYP/6-311++G** level. Hydrogen fluoride was found to have a particularly strong interaction with SO 3, forming an electron donor acceptor complex. Similarities to the hydrolysis of SO 3 to form sulfuric acid are discussed and the relative acidities of the halo-sulfonic acid series are evaluated and compared in the same context to sulfuric and perchloric acids.

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A Study of K/Ti-co-doped NaAlH4 on Thermodynamic Tailoring, Surplus Hydrogen Amount and Metal Hydride Molar Volume

10.26434/chemrxiv.13857623.v1 ◽

2021 ◽

Author(s):

Roland Hermann Pawelke

Keyword(s):

Hydrogen Storage ◽

Molar Volume ◽

Metal Hydride ◽

Chemical Potential ◽

Reaction Pathway ◽

Ideal Gas ◽

Point Of View ◽

Phase Point ◽

Desorption Enthalpy ◽

Co Doped

A remarkable finding of metal hydride hydrogen storage is that substituting 4 mol % sodium by potassium in 4 mol % Ti-doped NaAlH4 raises the reversible hydrogen storage capacity from 3.3 % w/w H to 4.7 % w/w H. This increase by 42% is concomitant with a slightly lower desorption enthalpy: intriguingly enough, it is substantially more hydrogen capacity at slightly less desorption enthalpy. The general solution to that puzzle has been already derived from a gas phase point of view, taking advantage of the equilibrium nature of the matter, which thus comes in terms of an ideal gas chemical potential. However, it is also interesting to investigate for the flipside effect in the sorbent phase, affecting molar volume. This paper elucidates by the example of K/Ti-co-doped NaAlH4 the relation of doping modifications to surplus hydrogen amount and hydride molar volume, defining the term “reaction pathway” in this context, yielding the according figures.

Download Full-text