Unveiling the redox-active character of imidazolin-2-thiones derived from amino-substituted N-heterocyclic carbenes

2018 ◽  
Vol 54 (55) ◽  
pp. 7653-7656 ◽  
Author(s):  
Mirko Ruamps ◽  
Stéphanie Bastin ◽  
Lionel Rechignat ◽  
Alix Sournia-Saquet ◽  
Dmitry A. Valyaev ◽  
...  
Keyword(s):  
Heterocyclic Carbenes ◽  
Computational Studies ◽  
Redox Active

Spectroscopic, structural and computational studies on the amino-substituted imidazolin-2-thiones reveal the imidazolyl ring to be redox active.

Electronic, Optical, and Computational Studies of a Redox-Active Napthalenediimide-Based Coordination Polymer

2013 ◽  
Vol 52 (24) ◽  
pp. 14246-14252 ◽  
Author(s):  
Chanel F. Leong ◽  
Bun Chan ◽  
Thomas B. Faust ◽  
Peter Turner ◽  
Deanna M. D’Alessandro
Keyword(s):  
Coordination Polymer ◽  
Computational Studies ◽  
Redox Active

scholarly journals An Iron Pyridyl-Carbene Catalyst for Low Overpotential CO2 reduction to CO: Mechanistic Comparisons with the Ruthenium Analogue and Photochemical Promotion

2020 ◽  
Author(s):  
Sergio Gonell ◽  
Julio Lloret ◽  
Alexander Miller
Keyword(s):  
Co2 Reduction ◽  
Iron Complexes ◽  
Transition Metal Ions ◽  
Ruthenium Catalysts ◽  
Computational Studies ◽  
Chelating Ligands ◽  
Faradaic Efficiency ◽  
Mechanistic Insight ◽  
Redox Active ◽  
Improved Performance

<div><div><div><p>Electrocatalysts for CO2 reduction based on first row transition metal ions have attracted attention as abundant and affordable candidates for energy conversion applications. We hypothesized that a successful strategy in ruthenium electrocatalyst design, featuring two chelating ligands that can be individually tuned to adjust the overpotential and catalytic activity, could be equally applicable in the analogous iron complexes. New iron complexes supported by a redox-active 2,2':6',2''-terpyridine (tpy) ligand and strong trans effect pyridyl- N-heterocyclic carbene ligand (1-methyl-benzimidazol-2-ylidene-3-(2-pyridine)) were synthesized, and these isostructural analogues to leading ruthenium catalysts were also found to be active CO2 reduction electrocatalysts. Electrochemical and computational studies reveal completely distinct mechanisms for the iron and ruthenium complexes, with hemilability in the iron system enabling electrocatalysis at overpotentials as low as 150 mV (ca. 500 mV lower than the ruthenium analogue). Cyclic voltammetry studies elucidated the mechanism of the net 4e–/2H+ process that occurs within the single reductive feature, with an iron solvento complex undergoing reduction, CO2 activation, and further reduction to an iron carbonyl. The mechanistic insight guided development of photoelectrocatalytic conditions under a continuous flow of CO2 that exhibited improved performance, with Faradaic efficiency up to 99%.</p></div></div></div>

scholarly journals Copper catalysis with redox-active ligands

2020 ◽  
Vol 16 ◽  
pp. 858-870 ◽  
Author(s):  
Agnideep Das ◽  
Yufeng Ren ◽  
Cheriehan Hessin ◽  
Marine Desage-El Murr
Keyword(s):  
Electron Transfer ◽  
Coordination Sphere ◽  
Copper Complexes ◽  
Heterocyclic Carbenes ◽  
Metal Center ◽  
Copper Catalysis ◽  
Redox Active Ligands ◽  
Elementary Steps ◽  
Cooperative Catalysis ◽  
Redox Active

Copper catalysis finds applications in various synthetic fields by utilizing the ability of copper to sustain mono- and bielectronic elementary steps. Further to the development of well-defined copper complexes with classical ligands such as phosphines and N-heterocyclic carbenes, a new and fast-expanding area of research is exploring the possibility of a complementing metal-centered reactivity with electronic participation by the coordination sphere. To achieve this electronic flexibility, redox-active ligands can be used to engage in a fruitful “electronic dialogue” with the metal center, and provide additional venues for electron transfer. This review aims to present the latest results in the area of copper-based cooperative catalysis with redox-active ligands.

Cationic Iridium Complexes Containing Anionic Iridium Counterions Supported by Redox-Active N-Heterocyclic Carbenes

2013 ◽  
Vol 32 (15) ◽  
pp. 4334-4341 ◽  
Author(s):  
Kuppuswamy Arumugam ◽  
Jinho Chang ◽  
Vincent M. Lynch ◽  
Christopher W. Bielawski
Keyword(s):  
Heterocyclic Carbenes ◽  
Iridium Complexes ◽  
Redox Active

Redox-Active N-Heterocyclic Carbenes: Design, Synthesis, and Evaluation of Their Electronic Properties

2009 ◽  
Vol 28 (23) ◽  
pp. 6695-6706 ◽  
Author(s):  
Evelyn L. Rosen ◽  
C. Daniel Varnado ◽  
Andrew G. Tennyson ◽  
Dimitri M. Khramov ◽  
Justin W. Kamplain ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Heterocyclic Carbenes ◽  
Design Synthesis ◽  
Redox Active

Experimental and Computational Studies on the Mechanism of Zwitterionic Ring-Opening Polymerization of δ-Valerolactone with N-Heterocyclic Carbenes

2014 ◽  
Vol 118 (24) ◽  
pp. 6553-6560 ◽  
Author(s):  
Ashwin K. Acharya ◽  
Young A. Chang ◽  
Gavin O. Jones ◽  
Julia E. Rice ◽  
James L. Hedrick ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Heterocyclic Carbenes ◽  
Computational Studies

scholarly journals Towards the Preparation of Stable Cyclic Amino(ylide)Carbenes

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 796 ◽  
Author(s):  
Henning Steinert ◽  
Christopher Schwarz ◽  
Alexander Kroll ◽  
Viktoria H. Gessner
Keyword(s):  
Heterocyclic Carbenes ◽  
Computational Studies ◽  
Alkyl Groups ◽  
Sulfonium Ylides ◽  
Careful Design ◽  
Bridgehead Position

Cyclic amino(ylide)carbenes (CAYCs) are the ylide-substituted analogues of N-heterocyclic Carbenes (NHCs). Due to the stronger π donation of the ylide compared to an amino moiety they are stronger donors and thus are desirable ligands for catalysis. However, no stable CAYC has been reported until today. Here, we describe experimental and computational studies on the synthesis and stability of CAYCs based on pyrroles with trialkyl onium groups. Attempts to isolate two CAYCs with trialkyl phosphonium and sulfonium ylides resulted in the deprotonation of the alkyl groups instead of the formation of the desired CAYCs. In case of the PCy3-substituted system, the corresponding ylide was isolated, while deprotonation of the SMe2-functionalized compound led to the formation of ethene and the thioether. Detailed computational studies on various trialkyl onium groups showed that both the α- and β-deprotonated compounds were energetically favored over the free carbene. The most stable candidates were revealed to be α-hydrogen-free adamantyl-substituted onium groups, for which β-deprotonation is less favorable at the bridgehead position. Overall, the calculations showed that the isolation of CAYCs should be possible, but careful design is required to exclude decomposition pathways such as deprotonations at the onium group.

scholarly journals An Iron Pyridyl-Carbene Catalyst for Low Overpotential CO2 reduction to CO: Mechanistic Comparisons with the Ruthenium Analogue and Photochemical Promotion

2020 ◽  
Author(s):  
Sergio Gonell ◽  
Julio Lloret ◽  
Alexander Miller
Keyword(s):  
Co2 Reduction ◽  
Iron Complexes ◽  
Transition Metal Ions ◽  
Ruthenium Catalysts ◽  
Computational Studies ◽  
Chelating Ligands ◽  
Faradaic Efficiency ◽  
Mechanistic Insight ◽  
Redox Active ◽  
Improved Performance

<div><div><div><p>Electrocatalysts for CO2 reduction based on first row transition metal ions have attracted attention as abundant and affordable candidates for energy conversion applications. We hypothesized that a successful strategy in ruthenium electrocatalyst design, featuring two chelating ligands that can be individually tuned to adjust the overpotential and catalytic activity, could be equally applicable in the analogous iron complexes. New iron complexes supported by a redox-active 2,2':6',2''-terpyridine (tpy) ligand and strong trans effect pyridyl- N-heterocyclic carbene ligand (1-methyl-benzimidazol-2-ylidene-3-(2-pyridine)) were synthesized, and these isostructural analogues to leading ruthenium catalysts were also found to be active CO2 reduction electrocatalysts. Electrochemical and computational studies reveal completely distinct mechanisms for the iron and ruthenium complexes, with hemilability in the iron system enabling electrocatalysis at overpotentials as low as 150 mV (ca. 500 mV lower than the ruthenium analogue). Cyclic voltammetry studies elucidated the mechanism of the net 4e–/2H+ process that occurs within the single reductive feature, with an iron solvento complex undergoing reduction, CO2 activation, and further reduction to an iron carbonyl. The mechanistic insight guided development of photoelectrocatalytic conditions under a continuous flow of CO2 that exhibited improved performance, with Faradaic efficiency up to 99%.</p></div></div></div>

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