Hydrogen splitting by pyramidalized 13–15 donor–acceptor cryptands: A computational study

El‐Hamdi, Majid; Timoshkin, Alexey Y.

doi:10.1002/jcc.25845

Cited by 6 publications

(23 citation statements)

References 48 publications

(43 reference statements)

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“…29 Cryptands based on bora-and aza-adamantanes were computationally studied for their abilities to activate and heterolytically split dihydrogen (Figure 9). 30 The combination of non-fluorinated 1-ala-and 1-boraadamantane with 1-azaadamantane spaced by a linker being a benzene, anthracene or phenanthrene moiety were highlighted to allow hydrogen heterolytic splitting via an endergonic process.…”

Section: Applications Of Non-planar Alkyl Boranes and Boronatesmentioning

confidence: 99%

Non-planar Boron Lewis Acids Taking the Next Step: Development of Tunable Lewis Acids, Lewis Superacids and Bifunctional Catalysts

Chardon

Osi²,

Mahaut³

et al. 2020

Synlett

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Although boron Lewis acids commonly adopt a trigonal planar geometry, a number of compounds in which the trivalent boron atom is located in a pyramidal environment have been described. This review will highlight the recent developments of the chemistry and applications of non-planar boron Lewis acids, including a series of non-planar triarylboranes derived from the triptycene core. A thorough analysis of the properties and of the influence of the pyramidalization of boron Lewis acids on their stereoelectronic properties and reactivities is presented based on recent theoretical and experimental studies.1 Non-planar Trialkylboranes2 Non-planar Alkyl and Aryl-Boronates3 Non-planar Triarylboranes and Alkenylboranes3.1 Previous Investigations on Bora Barrelenes and Triptycenes3.2 Recent Work on Boratriptycenes from Our Research Group4 Applications of Non-planar Boranes4.1 Non-planar Alkyl Boranes and Boronates4.2 Non-planar Triarylboranes (Boratriptycenes)5 Other Non-planar Group 13 Lewis Acids6 Further Work and Perspectives

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Section: Applications Of Non-planar Alkyl Boranes and Boronatesmentioning

confidence: 99%

Non-planar Boron Lewis Acids Taking the Next Step: Development of Tunable Lewis Acids, Lewis Superacids and Bifunctional Catalysts

Chardon

Osi²,

Mahaut³

et al. 2020

Synlett

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“…The importance of dihydrogen bonds for hydrogen splitting was noted by Repo et al The difference in NPA charges between two H atoms in TS2 is 0.35e (NPA charges for H – and H + are −0.16 and +0.19e). A linear H–H–P orientation was observed for the intermediates and TS formed by DA cryptands based on boraadamantane and indicates electron donation of the Lewis base to the antibonding σ* orbital of the hydrogen molecule. The large difference in the geometry of the first B(C 6 Me 4 ) 3 CH-H 2 + P t Bu 3 intermediate (Figure b) and TS2 (Figure c) contributes to the sizable (49 kJ·mol –1 ) activation barrier between this intermediate and the final [HP t Bu 3 ] + [HB(C 6 Me 4 ) 3 CH] − product.…”

Section: Resultsmentioning

confidence: 91%

“…These complexes are predicted to split H 2 endergonically with large barriers and therefore are not suitable for practical applications. Note however that artificially constrained donor–acceptor cryptands, featuring spatially separated Al and N centers preventing DA bond formation, are predicted to be highly active toward molecular hydrogen. , …”

Section: Resultsmentioning

confidence: 99%

“…The classical example of pyramidal group 13 Lewis acid is boraadamantane, which forms with azaadamantane a very strongly bound molecular complex, stable in air . Systems based on bora- and ala-adamantane scaffolds connected by rigid aromatic spacers were designed and computationally studied . Results indicate the principal possibility of hydrogen activation by group 13–15 adamantane-based FLPs, with donor and acceptor fragments separated by a rigid spacer …”

Section: Introductionmentioning

confidence: 99%

“…Systems based on bora- and ala-adamantane scaffolds connected by rigid aromatic spacers were designed and computationally studied . Results indicate the principal possibility of hydrogen activation by group 13–15 adamantane-based FLPs, with donor and acceptor fragments separated by a rigid spacer …”

Section: Introductionmentioning

confidence: 99%

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Hydrogen Activation by Frustrated and Not So Frustrated Lewis Pairs Based on Pyramidal Lewis Acid 9-Boratriptycene: A Computational Study

Pomogaeva

Timoshkin

2022

ACS Omega

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Structural features and reactivity of frustrated Lewis pairs (FLPs) formed by pyramidal group 13 Lewis acids based on 9-bora and 9-alatriptycene and bulky phosphines P t Bu 3 , PPh 3 , and PCy 3 are considered at the M06-2X/def2-TZVP level of theory. Classic FLP is formed only in the B(C 6 Me 4 ) 3 CH/P t Bu 3 system, while both FLP and donor−acceptor (DA) complex are observed in the B(C 6 F 4 ) 3 CF/P t Bu 3 system. Formation of DA complexes was observed in other systems; the B(C 6 H 4 ) 3 CH•P t Bu 3 complex features an elongated DA bond and can be considered a "latent" FLP. Transition states and reaction pathways for molecular hydrogen activation have been obtained. Processes of heterolytic hydrogen splitting are energetically more favored in solution compared to the gas phase, while activation energies in the gas phase and in solution are close. The alternative processes of hydrogenation of B−C or Al−C bonds in the source pyramidal Lewis acids in the absence of a Lewis base are exergonic but have larger activation energies than those for heterolytic hydrogen splitting. The tuning of Lewis acidity of 9-boratriptycene by changing the substituents allows one to control its reactivity with respect to hydrogen activation. Interestingly, the most promising system from the practical point of view is the DA complex B(C 6 H 4 ) 3 CH•P t Bu 3 , which is predicted to provide both low activation energy and thermodynamic reversibility of the heterolytic hydrogen splitting process. It appears that such "not so frustrated" or "latent" FLPs are the best candidates for reversible heterolytic hydrogen splitting.

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The Field of Main Group Lewis Acids and Lewis Superacids: Important Basics and Recent Developments

Timoshkin

2023

Chemistry A European J

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New developments in the field of Lewis acidity are highlighted, with the focus of novel Lewis acids and Lewis superacids of group 2, 13, 14, and 15 elements. Several important basics, illustrated by modern examples (classification of Donor‐Acceptor (DA) complexes, amphoteric nature of any compound in terms of DA interactions, reorganization energies of main group Lewis acids and the role of the energies of frontier orbitals) are presented and discussed. It is emphasized that the Lewis acidity phenomena are general and play vital role in different areas of chemistry: from weak “atomophilic” interactions to the complexes of Lewis superacids.

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Hydrogen splitting by pyramidalized 13–15 donor–acceptor cryptands: A computational study

Cited by 6 publications

References 48 publications

Non-planar Boron Lewis Acids Taking the Next Step: Development of Tunable Lewis Acids, Lewis Superacids and Bifunctional Catalysts

Non-planar Boron Lewis Acids Taking the Next Step: Development of Tunable Lewis Acids, Lewis Superacids and Bifunctional Catalysts

Hydrogen Activation by Frustrated and Not So Frustrated Lewis Pairs Based on Pyramidal Lewis Acid 9-Boratriptycene: A Computational Study

The Field of Main Group Lewis Acids and Lewis Superacids: Important Basics and Recent Developments

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