Influence of Sterically Demanding Carbene Ligation on Catalytic Behavior and Thermal Stability of Ruthenium Olefin Metathesis Catalysts

1999 ◽  
Vol 18 (25) ◽  
pp. 5375-5380 ◽  
Author(s):  
Jinkun Huang ◽  
Hans-Jörg Schanz ◽  
Edwin D. Stevens ◽  
Steven P. Nolan
Keyword(s):  
Thermal Stability ◽  
Olefin Metathesis ◽  
Catalytic Behavior ◽  
Sterically Demanding ◽  
Metathesis Catalysts ◽  
Thermal Stability Of

scholarly journals Ruthenium indenylidene “1st generation” olefin metathesis catalysts containing triisopropyl phosphite

2015 ◽  
Vol 11 ◽  
pp. 1520-1527 ◽  
Author(s):  
Stefano Guidone ◽  
Fady Nahra ◽  
Alexandra M Z Slawin ◽  
Catherine S J Cazin
Keyword(s):  
Experimental Data ◽  
Thermal Stability ◽  
Olefin Metathesis ◽  
Synergistic Effects ◽  
Metathesis Reactions ◽  
Metathesis Catalysts ◽  
Ru Species

The reaction of triisopropyl phosphite with phosphine-based indenylidene pre-catalysts affords “1st generation” cis-complexes. These have been used in olefin metathesis reactions. The cis-Ru species exhibit noticeable differences with the trans-Ru parent complexes in terms of structure, thermal stability and reactivity. Experimental data underline the importance of synergistic effects between phosphites and L-type ligands.

scholarly journals The activity of indenylidene derivatives in olefin metathesis catalysts

2018 ◽  
Vol 14 ◽  
pp. 2956-2963 ◽  
Author(s):  
Maria Voccia ◽  
Steven P Nolan ◽  
Luigi Cavallo ◽  
Albert Poater
Keyword(s):  
Olefin Metathesis ◽  
Density Functional ◽  
Bond Orders ◽  
Metathesis Reaction ◽  
Functional Theory ◽  
New Family ◽  
Sterically Demanding ◽  
Electronic Parameters ◽  
Metathesis Catalysts ◽  
Dissociation Step

The first turnover event of an olefin metathesis reaction using a new family of homogenous Ru-based catalysts bearing modified indenylidene ligands has been investigated, using methoxyethylene as a substrate. The study is carried out by means of density functional theory (DFT). The indenylidene ligands are decorated with ortho-methyl and isopropyl groups at both ortho positions of their phenyl ring. DFT results highlight the more sterically demanding indenylidenes have to undergo a more exothermic first phosphine dissociation step. Overall, the study emphasises advantages of increased steric hindrance in promoting the phosphine release, and the relative stability of the corresponding metallacycle over classical ylidene ligands. Mayer bond orders and steric maps provide structural reasons for these effects, whereas NICS aromaticity and conceptual DFT confirm that the electronic parameters do not play a significant role.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

Thermal stability of Al-Cu-Fe icosahedral alloys

1991 ◽  
Vol 1 (12) ◽  
pp. 1823-1836 ◽  
Author(s):  
M. Bessière ◽  
A. Quivy ◽  
S. Lefebvre ◽  
J. Devaud-Rzepski ◽  
Y. Calvayrac
Keyword(s):  
Thermal Stability ◽  
Thermal Stability Of

Practical criteria for the thermal stability of a unidimensional superconductor

1994 ◽  
Vol 4 (4) ◽  
pp. 653-657
Author(s):  
B. Bonzi ◽  
M. El Khomssi ◽  
H. Lanchon-Ducauquis
Keyword(s):  
Thermal Stability ◽  
Thermal Stability Of

Time and thermal stability of magnetic properties of amorphous Fe80TM3B17 alloys

1998 ◽  
Vol 08 (PR2) ◽  
pp. Pr2-63-Pr2-66 ◽  
Author(s):  
R. Varga ◽  
P. Vojtaník ◽  
A. Lovas
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Thermal Stability Of

Thermal stability of organic-inorganic nanocomposites based on system of dimethacrylate-tetraethoxysilane and their kinetic features

2016 ◽  
Vol 38 (3) ◽  
pp. 211-217
Author(s):  
G.I. Khovanets’ ◽  
◽  
O.Y. Makido ◽  
V.V. Kochubey ◽  
Y.G. Medvedevskikh ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Inorganic Nanocomposites ◽  
Thermal Stability Of ◽  
Kinetic Features
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