Breaking the Myth of the Recalcitrant Chemisorbed Hydrogens on Boron Nitride Nanotubes: A Theoretical Perspective

Roy, Lisa; Mittal, Samyak; Paul, Ankan

doi:10.1002/ange.201107962

Cited by 10 publications

(1 citation statement)

References 54 publications

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“…Thermal corrections and entropy contributions to the Gibbs energy were incorporated from the gas phase frequency calculations at 1 atm pressure and 298 K. For solvent-phase entities, the entropy used for estimating solvent-phase free energies was derived by scaling the corresponding gas-phase entropies computed using the ideal-gas model by a factor of 0.5. This is a standard approximation that has been used in other quantum chemical studies. − For H 2 (g) and N 2 (g), we have taken the gas phase entropy (1.0 scaling factor applied to entropy obtained from gas phase quantum chemical model). To check the reliability of the results predicted by the B3PW91-D functional, we did single-point solvent-phase calculations using the CPCM model with some other widely used density functionals, such as B3LYP, M06, M06L, ωB97XD, TPSSh, LC-ωPBE, etc., on certain crucial intermediates and transition states obtained from B3PW91-D/BS1 gas-phase geometry optimizations.…”

Section: Computational Detailsmentioning

confidence: 99%

Theoretical Studies on the Mechanism of Homogeneous Catalytic Olefin Hydrogenation and Amine–Borane Dehydrogenation by a Versatile Boryl-Ligand-Based Cobalt Catalyst

Ganguly

Malakar

2015

ACS Catal.

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We have conducted mechanistic investigations using dispersion-corrected hybrid density functional theory on three different homogeneous processes: (a) hydrogenation of styrene using H2, (b) dehydrogenation of amine–borane, and (c) transfer hydrogenation of styrene using amine–borane catalyzed by a boryl-ligated Co-based catalytic system, LCo(N2) (where L = meridional bis-phosphinoboryl (PBP) ligand), recently developed by Peters and co-workers (Lin, T.-P; Peters, J. C. J. Am. Chem. Soc. 2013, 135, 15310–15313). Our studies reveal that all three catalytic processes are facilitated by the same active species, which is of the form LCo(H)2. The formation of the active catalytic species in turn determines the rate-determining barrier (RDB) for the hydrogenation reactions of the olefin and also for the dehydrogenation reaction of amine–borane. We predict that the RDB for hydrogenation of styrene under H2 atmosphere is 17.3 kcal/mol, which occurs through a channel that involves switching of a singlet electronic ground state (S0) of the organometallic catalytic species to its low-lying triplet electronic state (T1) and returning back to the singlet surface through minimum energy crossing points along the reaction coordinate. Alternatively, we estimate the RDB to be 19.4 kcal/mol, slightly higher than that of the previous channel, if only the singlet spin state surface is considered. We find that the associated RDB for both the dehydrogenation of amine–borane (NMe2H-BH3) and transfer hydrogenation of styrene by amine–borane are higher than the hydrogenation of olefin using H2(g) and is predicted to be 24.7 kcal/mol. In addition, we show that in the reaction involving amine–borane, the active catalytic species (LCo(H)2) can get deactivated by forming a hydridoborane cobalt tetrahydridoborate complex, which happens through an SN2 type nucleophilic attack by the LCo(H)2 on amine–borane.

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Section: Computational Detailsmentioning

confidence: 99%

Theoretical Studies on the Mechanism of Homogeneous Catalytic Olefin Hydrogenation and Amine–Borane Dehydrogenation by a Versatile Boryl-Ligand-Based Cobalt Catalyst

Ganguly

Malakar

2015

ACS Catal.

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A Metal‐Free Strategy to Release Chemisorbed H₂ from Hydrogenated Boron Nitride Nanotubes

2014

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Chemisorbed hydrogen on boron nitride nanotubes (BNNT) can only be released thermally at very high temperatures above 350 8C. However, no catalyst has been identified that could liberate H 2 from hydrogenated BN nanotubes under moderate conditions. Using different density functional methods we predict that the desorption of chemisorbed hydrogen from hydrogenated BN nanotubes can be facilitated catalytically by triflic acid at low free-energy activation barriers and appreciable rates under metal free conditions and mildly elevated temperatures (40-50 8C). Our proposed mechanism shows that the acid is regenerated in the process and can further facilitate similar catalytic release of H 2 , thus suggesting all the chemisorbed hydrogen on the surface of the hydrogenated nanotube can be released in the form of H 2 . These findings essentially raise hope for the development of a sustainable chemical hydrogen storage strategy in BN nanomaterials.

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Amine–Boranes as Transfer Hydrogenation and Hydrogenation Reagents: A Mechanistic Perspective

2021

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Transfer hydrogenation (TH) has historically been dominated by Meerwein–Ponndorf–Verley (MPV) reactions. However, with growing interest in amine–boranes, not least ammonia–borane (H3N⋅BH3), as potential hydrogen storage materials, these compounds have also started to emerge as an alternative reagent in TH reactions. In this Review we discuss TH chemistry using H3N⋅BH3 and their analogues (amine–boranes and metal amidoboranes) as sacrificial hydrogen donors. Three distinct pathways were considered: 1) classical TH, 2) nonclassical TH, and 3) hydrogenation. Simple experimental mechanistic probes can be employed to distinguish which pathway is operating and computational analysis can corroborate or discount mechanisms. We find that the pathway in operation can be perturbed by changing the temperature, solvent, amine–borane, or even the substrate used in the system, and subsequently assignment of the mechanism can become nontrivial.

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Breaking the Myth of the Recalcitrant Chemisorbed Hydrogens on Boron Nitride Nanotubes: A Theoretical Perspective

Cited by 10 publications

References 54 publications

Theoretical Studies on the Mechanism of Homogeneous Catalytic Olefin Hydrogenation and Amine–Borane Dehydrogenation by a Versatile Boryl-Ligand-Based Cobalt Catalyst

Theoretical Studies on the Mechanism of Homogeneous Catalytic Olefin Hydrogenation and Amine–Borane Dehydrogenation by a Versatile Boryl-Ligand-Based Cobalt Catalyst

A Metal‐Free Strategy to Release Chemisorbed H₂ from Hydrogenated Boron Nitride Nanotubes

Amine–Boranes as Transfer Hydrogenation and Hydrogenation Reagents: A Mechanistic Perspective

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Breaking the Myth of the Recalcitrant Chemisorbed Hydrogens on Boron Nitride Nanotubes: A Theoretical Perspective

Cited by 10 publications

References 54 publications

Theoretical Studies on the Mechanism of Homogeneous Catalytic Olefin Hydrogenation and Amine–Borane Dehydrogenation by a Versatile Boryl-Ligand-Based Cobalt Catalyst

Theoretical Studies on the Mechanism of Homogeneous Catalytic Olefin Hydrogenation and Amine–Borane Dehydrogenation by a Versatile Boryl-Ligand-Based Cobalt Catalyst

A Metal‐Free Strategy to Release Chemisorbed H2 from Hydrogenated Boron Nitride Nanotubes

Amine–Boranes as Transfer Hydrogenation and Hydrogenation Reagents: A Mechanistic Perspective

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A Metal‐Free Strategy to Release Chemisorbed H₂ from Hydrogenated Boron Nitride Nanotubes