Dihydrogen‐Catalyzed Reversible Carbon–Hydrogen and Nitrogen–Hydrogen Bond Formation in Organometallic Iridium Complexes

Valpuesta, José E. Villar; Rendón, Nuria; López‐Serrano, Joaquín; Poveda, Manuel L.; Sánchez, Luis; Álvarez, Eleuterio; Carmona, Ernesto

doi:10.1002/anie.201201811

Cited by 13 publications

(36 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The free-energy barrier height for the hydrogen assisted H-atom transfer from Ir to N of the amino group was found to be 16.4 kcal mol −1 , which is significantly lower than the original H 2 -catalyzed barrier height of 28.7 kcal mol −1 calculated in (19) for the second, rate-limiting step that involves H 2 -addition/H-transfer (scrambling) reaction, not to mention the much higher barrier of 48 kcal mol −1 for the uncatalyzed reaction (vide infra).…”

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 68%

“…Following the DHC-concept, a relay transport of H-atoms mediated by dihydrogen could be expected to occur between the hydridic and protic atoms (proton-hydride exchange), as well as between the metal center and either the N-atom of the amido group or the C-atom of the CH 3 group. Our preliminary illustrative calculations using the same B3LYP/LanL2DZ method employed in (19) indeed demonstrated the relevance of H2-RT mechanism to such processes (vide infra).…”

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 77%

“…An interconversion of two iridium-aminopyridinate complexes supported by dihydrogen (1 and 2 in Fig. 9), has been recently observed experimentally and studied theoretically by Valpuesta et al (19).…”

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 88%

“…Assuming that this is not the result of the model limitations, a possible scenario can be suggested involving the direct, first step reaction, as described by Valpuesta et al (19), followed by the H2-RT lower-energy-barrier reaction illustrated in Fig. 10, i.e., via a mixed mechanism involving both the simple H-atom transfer mechanism suggested in (19) and the DHC (H2-RT) processes proposed in the current work. More detailed explorations and extended models are required to obtain more quantitative results.…”

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 93%

“…Two mechanisms have been studied theoretically by Valpuesta et al (19), without or with participation of dihydrogen. Mechanism (i) initiates an intramolecular oxidative addition of a methyl C-H bond to Ir followed by the hydride migration onto the metal-bound amido nitrogen, whereas mechanism (ii) involves an initial dihydrogen addition to the metal, followed by the same sequence of processes: hydride migration and methyl CH oxidative addition plus dihydrogen elimination (19). The overall barrier for mechanism (i) has been found to be too high ( G = is ca.…”

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 97%

See 4 more Smart Citations

Dihydrogen Catalysis: A Remarkable Avenue in the Reactivity of Molecular Hydrogen

Asatryan

Ruckenstein

2014

Catalysis Reviews

View full text Add to dashboard Cite

Molecular hydrogen is the simplest and most abundant compound in the universe and is involved in numerous industrial chemical processes. In conventional chemistry, dihydrogen typically plays the role of a reductant and a reagent for homogeneous and heterogeneous hydrogenation processes such as the industrial and enzymatic ammonia formation, reduction of metallic ores and hydrogenation of unsaturated fats and oils. However, there are also processes in which molecular hydrogen participates as promoter, and even as catalyst. The catalytic role of the dihydrogen in free-valence migration in irradiated polymers and the interstellar isomerization of the formyl cation (protonated carbon monoxide) are well-documented examples of such processes. Recently, this issue has received new attention. Dihydrogen has been shown to play the role of a dehydrogenation catalyst (involving particularly metallocomplexes and inorganic materials), a relay (pass-on) transfer molecular agent and a transporter of protons.This review article, combined with original results, is focused on the mechanisms of the chemical processes where dihydrogen demonstrates catalytic behavior. We will call these processes (with somewhat broader meaning of the term) "dihydrogen catalysis" (DHC) which also includes the reactions mediated by transition metal dihydrides. Dihydrides are tentatively considered as pre-activated dihydrogen, coordinated to a metal center or implanted into a solid surface/support. DHC reactions are classified into five major reaction types: (i) dihydrogen-assisted relay transport of H-atoms (H2-RT); (ii) dihydrogen-assisted stepwise relay transport of H-atoms or of a free valence (sH2-RT); (iii) dihydrogen-assisted proton transport (H2-PT); (iv) dihydrogen-assisted dehydrogenation (H2-DeH); and (v) pre-activated dehydrogenation (PA-DeH). The classification of these mechanisms is Color versions of one or more of the figures in the article can be found online at www. tandfonline.com/lctr. 403 Downloaded by [George Mason University] at 02:43 28 September 2014 R. Asatryan and E. Ruckensteinbased on a detailed analysis of numerous potential energy surfaces studied by DFT and ab initio methods in conjunction with available experimental data. The H2-RT, H2-DeH, and PA-DeH processes occur via cyclic transition states. The relay H2-RT transport involves the H-H-H triad linked to both H-donor and H-acceptor centers, whereas the transition state ring in the H2-DeH dehydrogenation processes involves a H-H-H-H tetrad with the dihydrogen catalyst located in the middle. The H2-PT mechanism provides the transport of a proton mediated by dihydrogen combined in a triangular (H 3 + )-carrier unit. There are also practically important processes stimulated by dihydrogen such as the hydrogen spillover and hydrogen build-up in electronics, in which the catalytic role of dihydrogen is ambiguous, either because of the uncertainties in mechanisms, or prevailing traditional views. Some examples are briefly discussed in the framework of the concept of dihydrogen ...

show abstract

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 68%

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 77%

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 88%

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 93%

Section: (B) Models Involving Transition Metals Other Than Ironmentioning

confidence: 97%

See 3 more Smart Citations

Dihydrogen Catalysis: A Remarkable Avenue in the Reactivity of Molecular Hydrogen

Asatryan

Ruckenstein

2014

Catalysis Reviews

View full text Add to dashboard Cite

show abstract

Dihydrogen Catalysis of the Reversible Formation and Cleavage of CH and NH Bonds of Aminopyridinate Ligands Bound to (η⁵‐C₅Me₅)Ir^III

Zamorano

Rendón

López‐Serrano

et al. 2014

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

This study focuses on a series of cationic complexes of iridium that contain aminopyridinate (Ap) ligands bound to an (η(5) -C5 Me5 )Ir(III) fragment. The new complexes have the chemical composition [Ir(Ap)(η(5) -C5 Me5 )](+) , exist in the form of two isomers (1(+) and 2(+) ) and were isolated as salts of the BArF (-) anion (BArF =B[3,5-(CF3 )2 C6 H3 ]4 ). Four Ap ligands that differ in the nature of their bulky aryl substituents at the amido nitrogen atom and pyridinic ring were employed. In the presence of H2 , the electrophilicity of the Ir(III) centre of these complexes allows for a reversible prototropic rearrangement that changes the nature and coordination mode of the aminopyridinate ligand between the well-known κ(2) -N,N'-bidentate binding in 1(+) and the unprecedented κ-N,η(3) -pseudo-allyl-coordination mode in isomers 2(+) through activation of a benzylic C-H bond and formal proton transfer to the amido nitrogen atom. Experimental and computational studies evidence that the overall rearrangement, which entails reversible formation and cleavage of H-H, C-H and N-H bonds, is catalysed by dihydrogen under homogeneous conditions.

show abstract

Coordination Chemistry of Bulky Aminopryridinates with Main Group and Transition Metals

Noor

2021

Top Curr Chem (Z)

View full text Add to dashboard Cite

Dihydrogen‐Catalyzed Reversible Carbon–Hydrogen and Nitrogen–Hydrogen Bond Formation in Organometallic Iridium Complexes

Abstract: Dihydrogen at work! H2 catalyzes with high efficiency a prototropic rearrangement of aminopyridinate ligands bound to a {(η5‐C5Me5)IrIII} unit. The catalytic isomerization implies reversible formation and cleavage of HH, CH, and NH bonds.

Cited by 13 publications

References 50 publications

Dihydrogen Catalysis: A Remarkable Avenue in the Reactivity of Molecular Hydrogen

Dihydrogen Catalysis: A Remarkable Avenue in the Reactivity of Molecular Hydrogen

Dihydrogen Catalysis of the Reversible Formation and Cleavage of CH and NH Bonds of Aminopyridinate Ligands Bound to (η⁵‐C₅Me₅)Ir^III

Coordination Chemistry of Bulky Aminopryridinates with Main Group and Transition Metals

Contact Info

Product

Resources

About

Dihydrogen‐Catalyzed Reversible Carbon–Hydrogen and Nitrogen–Hydrogen Bond Formation in Organometallic Iridium Complexes

Abstract: Dihydrogen at work! H2 catalyzes with high efficiency a prototropic rearrangement of aminopyridinate ligands bound to a {(η5‐C5Me5)IrIII} unit. The catalytic isomerization implies reversible formation and cleavage of HH, CH, and NH bonds.

Cited by 13 publications

References 50 publications

Dihydrogen Catalysis: A Remarkable Avenue in the Reactivity of Molecular Hydrogen

Dihydrogen Catalysis: A Remarkable Avenue in the Reactivity of Molecular Hydrogen

Dihydrogen Catalysis of the Reversible Formation and Cleavage of CH and NH Bonds of Aminopyridinate Ligands Bound to (η5‐C5Me5)IrIII

Coordination Chemistry of Bulky Aminopryridinates with Main Group and Transition Metals

Contact Info

Product

Resources

About

Dihydrogen Catalysis of the Reversible Formation and Cleavage of CH and NH Bonds of Aminopyridinate Ligands Bound to (η⁵‐C₅Me₅)Ir^III