Room‐Temperature Activation of H2 by a Surface Frustrated Lewis Pair
20
Citation
42
Reference
10
Related Paper
Citation Trend
Abstract:
Abstract Surface frustrated Lewis pairs (SFLPs) have been implicated in the gas‐phase heterogeneous (photo)catalytic hydrogenation of CO 2 to CO and CH 3 OH by In 2 O 3− x (OH) y . A key step in the reaction pathway is envisioned to be the heterolysis of H 2 on a proximal Lewis acid–Lewis base pair, the SFLP, the chemistry of which is described as In⋅⋅⋅In‐OH + H 2 → In‐OH 2 + ⋅⋅⋅In‐H − . The product of the heterolysis, thought to be a protonated hydroxide Lewis base In‐OH 2 + and a hydride coordinated Lewis acid In‐H − , can react with CO 2 to form either CO or CH 3 OH. While the experimental and theoretical evidence is compelling for heterolysis of H 2 on the SFLP, all conclusions derive from indirect proof, and direct observation remains lacking. Unexpectedly, we have discovered rhombohedral In 2 O 3− x (OH) y can enable dissociation of H 2 at room temperature, which allows its direct observation by several analytical techniques. The collected analytical results lean towards the heterolysis rather than the homolysis reaction pathway.Keywords:
Heterolysis
Frustrated Lewis pair
Homolysis
Electron pair
D-mannitol
Abstract Surface frustrated Lewis pairs (SFLPs) have been implicated in the gas‐phase heterogeneous (photo)catalytic hydrogenation of CO 2 to CO and CH 3 OH by In 2 O 3− x (OH) y . A key step in the reaction pathway is envisioned to be the heterolysis of H 2 on a proximal Lewis acid–Lewis base pair, the SFLP, the chemistry of which is described as In⋅⋅⋅In‐OH + H 2 → In‐OH 2 + ⋅⋅⋅In‐H − . The product of the heterolysis, thought to be a protonated hydroxide Lewis base In‐OH 2 + and a hydride coordinated Lewis acid In‐H − , can react with CO 2 to form either CO or CH 3 OH. While the experimental and theoretical evidence is compelling for heterolysis of H 2 on the SFLP, all conclusions derive from indirect proof, and direct observation remains lacking. Unexpectedly, we have discovered rhombohedral In 2 O 3− x (OH) y can enable dissociation of H 2 at room temperature, which allows its direct observation by several analytical techniques. The collected analytical results lean towards the heterolysis rather than the homolysis reaction pathway.
Heterolysis
Frustrated Lewis pair
Homolysis
Electron pair
D-mannitol
Cite
Citations (20)
Heterolysis
Homolysis
Bond cleavage
Cleavage (geology)
Cite
Citations (1)
Abstract In heterolytic dediazoniations arenediazonium salts form aryl cations. The reaction rates are relatively slow; they depend only to a small extent on the solvent. It is shown that the solvents in which the heterolytic dediazoniation mechanism is predominant have a low nucleophilicity, whereas in solvents of high nucleophilicity homolysis of arenediazonium salts, i.e. the formation of aryl radicals and related intermediates, is favoured. Under comparable conditions, homolytic rates are faster than the corresponding rates of heterolysis. Homolysis is strongly enhanced by addition of nucleophiles which form relatively stable radicals by electron transfer. The ability of additives to catalyze homolysis of arenediazonium salts can be explained using the concept of a nucleofugic In the original proposal [32] we used the word nucleofugal. In keeping with a forthcoming proposal on nomenclature in physical organic chemistry by Commission III.2 (Physical Organic Chemistry) of IUPAC we now use the word nucleofugic. homolytic leaving group .
Homolysis
Heterolysis
Solvolysis
Aryl radical
Cite
Citations (45)
Frustrated Lewis pair
Heterolysis
Reactivity
Electron pair
Cleavage (geology)
Cite
Citations (0)
Heterolysis
Homolysis
Bond cleavage
Cite
Citations (6)
The heterolytic and homolytic N-NO bond dissociation energies of seven N-nitrosoindole derivatives were evaluated by using titration calorimetry and relative thermodynamic cycles.The energetic scales of the heterolytic and homolytic N-NO bond dissociation energies of N-nitrosoindoles cover the ranges from 206.1 to 246.2 kJ/mol and from 119.1 to 124.6 kJ/mol,respectively,which indicates that N-nitrosoindoles are much easier to release a NO radical(NO\5) rather than a NO cation(NO+).The estimation of the heterolytic and homolytic(N-NO)-\5 bond dissociation energies of the N-nitrosoindoles radical anions gives the energetic ranges from 25.5 to 33.4 kJ/mol and from 5.0 to 40.5 kJ/mol for the(N-NO)-\5 bond homolysis and heterolysis,respectively,which means that N-nitrosoindole radical anions are unstable at room temperature.
Heterolysis
Homolysis
Bond-dissociation energy
Bond cleavage
Bond energy
Cite
Citations (4)
Abstract Surface frustrated Lewis pairs (SFLPs) have been implicated in the gas‐phase heterogeneous (photo)catalytic hydrogenation of CO 2 to CO and CH 3 OH by In 2 O 3− x (OH) y . A key step in the reaction pathway is envisioned to be the heterolysis of H 2 on a proximal Lewis acid–Lewis base pair, the SFLP, the chemistry of which is described as In⋅⋅⋅In‐OH + H 2 → In‐OH 2 + ⋅⋅⋅In‐H − . The product of the heterolysis, thought to be a protonated hydroxide Lewis base In‐OH 2 + and a hydride coordinated Lewis acid In‐H − , can react with CO 2 to form either CO or CH 3 OH. While the experimental and theoretical evidence is compelling for heterolysis of H 2 on the SFLP, all conclusions derive from indirect proof, and direct observation remains lacking. Unexpectedly, we have discovered rhombohedral In 2 O 3− x (OH) y can enable dissociation of H 2 at room temperature, which allows its direct observation by several analytical techniques. The collected analytical results lean towards the heterolysis rather than the homolysis reaction pathway.
Heterolysis
Frustrated Lewis pair
Homolysis
Electron pair
D-mannitol
Cite
Citations (96)
The understanding of the mechanism by which frustrated Lewis pairs activate small molecules has been evolving with the discovery that both heterolytic and homolytic bond activation is possible. Herein we characterized a novel Lewis acidic aminoborane containing a phenothiazyl substituent and demonstrate its potential to catalytically promote the dehydrocoupling of tin hydrides. The reactivity observed implies this species promotes homolytic bond activation, however computational analysis suggests a heterolytic mechanism for this reaction. This result represents the first frustrated Lewis pair system to blur the lines between heterolytic and homolytic reactivity.
Heterolysis
Homolysis
Frustrated Lewis pair
Reactivity
Bond cleavage
Cite
Citations (0)
Forcing a square peg into a round hole: tBu2ImC: and B(C6F5)3 form a frustrated Lewis pair (FLP), allowing the synergistic activation of H2. On page 7428 ff., M. Tamm et al. describe how the irreversible formation of an abnormal carbene–borane adduct eliminates mismatching between acid and base so that this system can circumvent frustration at the expense of activity. In addition, D. W. Stephan and P. A. Chase demonstrate on page 7433 ff. that this FLP combination not only effects heterolytic cleavage of H2, but also of amine NH bonds.
Heterolysis
Frustrated Lewis pair
Boranes
Electron pair
Cleavage (geology)
Cite
Citations (1)
The understanding of the mechanism by which frustrated Lewis pairs activate small molecules has been evolving with the discovery that both heterolytic and homolytic bond activation is possible. Herein we characterized a novel Lewis acidic aminoborane containing a phenothiazyl substituent and demonstrate its potential to catalytically promote the dehydrocoupling of tin hydrides. The reactivity observed implies this species promotes homolytic bond activation, however computational analysis suggests a heterolytic mechanism for this reaction. This result represents the first frustrated Lewis pair system to blur the lines between heterolytic and homolytic reactivity.
Heterolysis
Homolysis
Frustrated Lewis pair
Reactivity
Bond cleavage
Cite
Citations (0)