ChemInform Abstract: Bronsted-Lowry Acid Strength of Metal Hydride and Dihydrogen Complexes

ChemInform ◽  
2016 ◽  
Vol 47 (40) ◽  
Author(s):  
Robert H. Morris
Keyword(s):  
Metal Hydride ◽  
Acid Strength ◽  
Dihydrogen Complexes

Localized-orbital locator (LOL) profiles of transition-metal hydride and dihydrogen complexes,

2009 ◽  
Vol 87 (7) ◽  
pp. 965-973 ◽  
Author(s):  
Heiko Jacobsen
Keyword(s):  
Transition Metal ◽  
Metal Hydride ◽  
Relativistic Effects ◽  
Kinetic Energy Density ◽  
Model Compounds ◽  
Dihydrogen Complexes ◽  
Different Types ◽  
Transition Metal Hydride ◽  
Localized Orbital ◽  
Hydride Ligands

A bond descriptor based on the kinetic-energy density, the localized-orbital locator (LOL), is used to characterize the nature of the chemical bond in transition-metal hydride and dihydrogen complexes. Cationic complexes of the iron triad [MH3(PMe3)4]+ (M = Fe, Ru, Os) serve as model compounds for transition-metal hydrogen bonding, since these complexes not only present examples for hydride as well as dihydrogen complexes, but for certain representatives, the two different types of metal–hydrogen bonds are realized within the same molecule. Both types of ligands show characteristic LOL profiles: (3,–3) Γ attractors in close vicinity to the H-atom for hydride ligands, and (3,–3) Γ attractors located between the two atoms for a dihydrogen ligand with νΓ-values of 0.8 and 0.9, respectively. In-between structures combine elements of the hydride and dihydrogen ligands. Relativistic effects on the relative stability of various isomers for the set of model compounds have been evaluated.

Heat Transfer in High-Pressure Metal Hydride Systems

2009 ◽  
Vol 16 (2) ◽  
pp. 189-203 ◽  
Author(s):  
Kyle C. Smith ◽  
Yuan Zheng ◽  
Timothy S. Fisher ◽  
Timothee L. Pourpoint ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Metal Hydride

Performance of Ag-HZSM-5 Zeolite Catalysts in n-heptane Conversion

2017 ◽  
Vol 68 (1) ◽  
pp. 116-120
Author(s):  
Iuliean Vasile Asaftei ◽  
Neculai Catalin Lungu ◽  
Lucian Mihail Birsa ◽  
Ioan Gabriel Sandu ◽  
Laura Gabriela Sarbu ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Metal Content ◽  
Pulse Method ◽  
Acid Strength ◽  
Strength Distribution ◽  
Zeolite Catalysts ◽  
Benzene Toluene ◽  
Acid Strength Distribution ◽  
Silver Cations ◽  
Heptane Conversion

The conversion of n-heptanes into aromatic hydrocarbons benzene, toluene and xylenes (BTX), by the chromatographic pulse method in the temperature range of 673 - 823K was performed over the HZSM-5 and Ag-HZSM-5 zeolites modified by ion exchange with AgNO3 aqueous solutions. The catalysts, HZSM-5 (SiO2/Al2O3 = 33.9), and Ag-HZSM-5 (Ag1-HZSM-5 wt. % Ag1.02, Ag2-HZSM-5 wt. % Ag 1.62; and Ag3-HZSM-5 wt. % Ag 2.05 having different acid strength distribution exhibit a conversion and a yield of aromatics depending on temperature and metal content. The yield of aromatic hydrocarbons BTX appreciably increased by incorporating silver cations Ag+ into HZSM-5.

Metal Hydride Preheater for the M2 Diesel Burner

1999 ◽  
Author(s):  
Joseph Gerstmann ◽  
Mark Golben
Keyword(s):  
Metal Hydride

Aromatization of C2-C6 Aliphatic Hydrocarbons on Copper-Containing ZSM-5 Zeolites

1992 ◽  
Vol 57 (12) ◽  
pp. 2553-2560
Author(s):  
Zdravka Popova ◽  
Katia Aristirova ◽  
Christo Dimitrov
Keyword(s):  
Copper Content ◽  
Acid Strength ◽  
The State ◽  
Aliphatic Hydrocarbons ◽  
Bronsted Acid ◽  
Ion Formation ◽  
Brönsted Acid ◽  
Wide Range ◽  
Carbenium Ion ◽  
Acid Centers

The aromatization of a wide range of model aliphatic and cycloaliphatic hydrocarbons (ethene, ethane, propene, n-hexane, 1-hexene, methylcyclopentane, cyclohexane, cyclohexene) on copper-containing NaZSM-5 and HZSM-5 zeolites has been investigated. It was established that the degree of aromatization is related to carbenium ion formation and depends on the acid strength and copper content of zeolite. Experiments with copper-containing samples reduced prior to use indicated the possibility to enhance the selectivity to aromatization. The change of the state of Cu2+ ions during catalytic experiments confirmed the assumption about participation of Cu0 simultaneously with the Bronsted acid centers in the dehydrogenation/hydrogenation steps.

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