A Chiral-at-Metal Iridium Catalyst with Two Simple but Sterically Demanding Cyclometalated N-Heterocyclic Carbene Ligands

2018 ◽  
Vol 2018 (22) ◽  
pp. 2500-2504 ◽  
Author(s):  
Yuqi Tan ◽  
Klaus Harms ◽  
Eric Meggers
Keyword(s):  
Carbene Ligands ◽  
Iridium Catalyst ◽  
Sterically Demanding

Design of Sterically Demanding, Electron-Rich Carbene Ligands with the Perimidine Scaffold

2007 ◽  
Vol 26 (11) ◽  
pp. 2885-2895 ◽  
Author(s):  
Patrick Bazinet ◽  
Tiow-Gan Ong ◽  
Julie S. O'Brien ◽  
Nathalie Lavoie ◽  
Eleanor Bell ◽  
...  
Keyword(s):  
Carbene Ligands ◽  
Sterically Demanding

Sterically Demanding, Bioxazoline-Derived N-Heterocyclic Carbene Ligands with Restricted Flexibility for Catalysis

2004 ◽  
Vol 126 (46) ◽  
pp. 15195-15201 ◽  
Author(s):  
Gereon Altenhoff ◽  
Richard Goddard ◽  
Christian W. Lehmann ◽  
Frank Glorius
Keyword(s):  
Carbene Ligands ◽  
Sterically Demanding

Sterically Demanding, Bioxazoline-Derived N-Heterocyclic Carbene Ligands with Restricted Flexibility for Catalysis.

ChemInform ◽  
2005 ◽  
Vol 36 (11) ◽  
Author(s):  
Gereon Altenhoff ◽  
Richard Goddard ◽  
Christian W. Lehmann ◽  
Frank Glorius
Keyword(s):  
Carbene Ligands ◽  
Sterically Demanding

Tunable iridium catalyst designs with bidentate N-heterocyclic carbene ligands for SABRE hyperpolarization of sterically hindered substrates

2020 ◽  
Vol 56 (98) ◽  
pp. 15466-15469
Author(s):  
Pierce Pham ◽  
Christian Hilty
Keyword(s):  
Exchange Rate ◽  
Sensitivity Enhancement ◽  
Carbene Ligands ◽  
Iridium Catalysts ◽  
Iridium Catalyst ◽  
Sterically Hindered ◽  
Nmr Sensitivity

A series of iridium catalysts provides NMR sensitivity enhancement using para-hydrogen. The substrate exchange rate can be tuned for optimal polarization by the choice of an aryl and a nucleophilic moiety in the catalyst.

Regioselective Gas-Phase n-Butane Transfer Dehydrogenation via Silica-Supported Pincer-Iridium Complexes

2020 ◽  
Author(s):  
Boris Sheludko ◽  
Cristina Castro ◽  
Chaitanya Khalap ◽  
Thomas Emge ◽  
Alan Goldman ◽  
...  
Keyword(s):  
Gas Phase ◽  
Active Site ◽  
Lower Cost ◽  
Open Systems ◽  
Iridium Complexes ◽  
Terminal Olefin ◽  
Molecular Precursors ◽  
Sterically Demanding ◽  
Olefin Production ◽  
Steam Cracking

<b>Abstract:</b> The production of olefins via on-purpose dehydrogenation of alkanes allows for a more efficient, selective and lower cost alternative to processes such as steam cracking. Silica-supported pincer-iridium complexes of the form [(≡SiO-<sup>R4</sup>POCOP)Ir(CO)] (<sup>R4</sup>POCOP = κ<sup>3</sup>-C<sub>6</sub>H<sub>3</sub>-2,6-(OPR<sub>2</sub>)<sub>2</sub>) are effective for acceptorless alkane dehydrogenation, and have been shown stable up to 300 °C. However, while solution-phase analogues of such species have demonstrated high regioselectivity for terminal olefin production under transfer dehydrogenation conditions at or below 240 °C, in open systems at 300 °C, regioselectivity under acceptorless dehydrogenation conditions is consistently low. In this work, complexes <a>[(≡SiO-<i><sup>t</sup></i><sup>Bu4</sup>POCOP)Ir(CO)] </a>(<b>1</b>) and [(≡SiO-<i><sup>i</sup></i><sup>Pr4</sup>PCP)Ir(CO)] (<b>2</b>) were synthesized via immobilization of molecular precursors. These complexes were used for gas-phase butane transfer dehydrogenation using increasingly sterically demanding olefins, resulting in observed selectivities of up to 77%. The results indicate that the active site is conserved upon immobilization.

Monodentate Trialkylphosphines: Privileged Ligands in Metal-catalyzed Crosscoupling Reactions

2020 ◽  
Vol 24 (3) ◽  
pp. 231-264 ◽  
Author(s):  
Kevin H. Shaughnessy
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Wide Range ◽  
Sterically Demanding ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Phosphines are widely used ligands in transition metal-catalyzed reactions. Arylphosphines, such as triphenylphosphine, were among the first phosphines to show broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich trialkylphosphines began to receive attention as supporting ligands. These ligands were found to be particularly effective at promoting oxidative addition in cross-coupling of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine, coupling of aryl bromides could be achieved at room temperature. More importantly, the less reactive, but more broadly available, aryl chlorides became accessible substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application in a wide range of late transition-metal catalyzed coupling reactions. This success has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review will discuss the general properties and features of monodentate trialkylphosphines and their application in cross-coupling reactions of C–X and C–H bonds.

Thermally Stable Half-Sandwich Benzhydryl Ln(II) (Ln = Sm, Yb) Complexes Supported by Sterically Demanding Carbazolyl and Fluorenyl Ligands

2019 ◽  
Vol 38 (24) ◽  
pp. 4615-4624 ◽  
Author(s):  
Alexander N. Selikhov ◽  
Andrey S. Shavyrin ◽  
Anton V. Cherkasov ◽  
Georgy K. Fukin ◽  
Alexander A. Trifonov
Keyword(s):  
Thermally Stable ◽  
Sterically Demanding ◽  
Half Sandwich

Hydrogen production from cellulose catalyzed by an iridium complex in ionic liquid under mild conditions

2021 ◽  
Author(s):  
Genki Toyooka ◽  
Toshiki Tanaka ◽  
Kenji Kitayama ◽  
Naoko Kobayashi ◽  
Takashi Watanabe ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Production ◽  
Iridium Complex ◽  
Simple Method ◽  
Mild Conditions ◽  
Iridium Catalyst

A new and simple method for hydrogen production from cellulose using an iridium catalyst and an ionic liquid under mild conditions was developed.

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