Carbene‐9‐BBN Ring Expansions as a Route to Intramolecular Frustrated Lewis Pairs for CO<sub>2</sub> Reduction

Wang, Tongen; Stephan, Douglas W.

doi:10.1002/chem.201304870

Cited by 169 publications

(92 citation statements)

References 52 publications

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“…Rivard reported the first example of boron hydride insertion into NHCs, which has been followed by a number of observations of analogous boron hydride reactivity . As of yet, there are no reports of analogous reactivity for the heavier group 13 elements.…”

Section: Resultsmentioning

confidence: 99%

Insertion of Group 12–16 Hydrides into NHCs: A Theoretical Investigation

Iversen

Dutton

Wilson

2017

Chemistry An Asian Journal

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Abstract:The endocyclic ring expansiono fN-heterocyclic carbene (NHC) rings by transitionm etal (group 12) and main group (group 13-16) elementh ydrides has been investigated in ac omputational study.I na ddition to previously reported insertion reactivity with Si, B, Be and Zn, similarr eactivity is predicted to be feasible for heavierg roup 13 elements (Al,G a, In, Tl), with the reaction barriersf or Al-Tl calculated to be lower than for boron.I nsertion is not expected with group 15-16 elementh ydrides, as the initial adduct formationist hermodynamically unfavorable. The reaction pathway with group 12 hydrides is calculated to be more favorable with two NHCs rather than as ingle NHC (analogous to Be), however hydride ring insertion with metal dihydrides is not feasible, but ratherareduced NHC is thermodynamically favored. For group 14, ring-insertion reactivityi sp redicted to be feasible with the heavier dihydrides. Trends in reactivity of element hydrides may be related to the protic or hydridic character of the elementhydrides.

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Section: Resultsmentioning

confidence: 99%

Insertion of Group 12–16 Hydrides into NHCs: A Theoretical Investigation

Iversen

Dutton

Wilson

2017

Chemistry An Asian Journal

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“…In a related study, Piers and coworkers 146 150 In closely related work, we reported the use of C 3 H 2 (NPR 2 ) 2 BC 8 H 14 (Scheme 19) as a catalyst which was derived from the insertion of C 3 H 2 (NPR 2 ) 2 into 9-BBN. 151 In a 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 further study, we 152 showed that hydroboration of CO 2 by 9-BBN is catalyzed by phosphine, affording a mixture of MeOB(C 8 H 14 ) and O(B(C 8 H 14 )) 2 in 98% yield with as little as 0.02% phosphine as the catalyst.…”

Section: Scheme 18 Stoichiometric Reductions Of Co 2 With P/al Flpsmentioning

confidence: 97%

Frustrated Lewis Pairs

2015

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The articulation of the notion of "frustrated Lewis pairs" (FLPs), which emerged from the discovery that H2 can be reversibly activated by combinations of sterically encumbered Lewis acids and bases, has prompted a great deal of recent activity. Perhaps the most remarkable consequence has been the development of FLP catalysts for the hydrogenation of a range of organic substrates. In the past 9 years, the substrate scope has evolved from bulky polar species to include a wide range of unsaturated organic molecules. In addition, effective stereoselective metal-free hydrogenation catalysts have begun to emerge. The mechanism of this activation of H2 has been explored, and the nature and range of Lewis acid/base combinations capable of effecting such activation have also expanded to include a variety of non-metal species. The reactivity of FLPs with a variety of other small molecules, including olefins, alkynes, and a range of element oxides, has also been developed. Although much of this latter chemistry has uncovered unique stoichiometric transformations, metal-free catalytic hydroamination, CO2 reduction chemistry, and applications in polymerization have also been achieved. The concept is also beginning to find applications in bioinorganic and materials chemistry as well as heterogeneous catalysis. This Perspective highlights many of these developments and discusses the relationship between FLPs and established chemistry. Some of the directions and developments that are likely to emerge from FLP chemistry in the future are also presented.

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“…1 Despite NHCs being considered to be robust spectator ligands in catalysis, the activation of C-N bonds has significant generality, being thus far observed for the elements Be, 2 B, [3][4][5] Si, 6 Ni, 7 and Zn. 1 Despite NHCs being considered to be robust spectator ligands in catalysis, the activation of C-N bonds has significant generality, being thus far observed for the elements Be, 2 B, [3][4][5] Si, 6 Ni, 7 and Zn.…”

Section: Introductionmentioning

confidence: 99%

Effects of the electronic structure of five-membered N-heterocyclic carbenes on insertion of silanes and boranes into the NHC C–N bond

2015

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The effect of varying the N-heterocyclic carbene (NHC) ligand on ring expansion and endocyclic C-N activation of NHCs by silanes and boranes has been investigated with theoretical methods. Five common NHCs were considered, including unsaturated, saturated, 3,4-methyl, 3,4-chloro substituted five-membered NHCs and a fused benzimidazole NHC. The substrates considered were Ph2SiH2 (with two hydrides migrating to the carbene carbon), H2BMe (two hydrides migrating), HBMe2 (hydride migration, followed by methyl migration) and BMe3 (two methyls migrating). Consistent with experimental observations, it was found that the kinetic barrier is lowest for the saturated NHC. The barrier is also quite low for the benzimidazole NHC. It was determined that the partial positive charge on the central carbene carbon in the initial adduct is inversely proportional to the magnitude of the activation barrier.

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Carbene‐9‐BBN Ring Expansions as a Route to Intramolecular Frustrated Lewis Pairs for CO₂ Reduction

Cited by 169 publications

References 52 publications

Insertion of Group 12–16 Hydrides into NHCs: A Theoretical Investigation

Insertion of Group 12–16 Hydrides into NHCs: A Theoretical Investigation

Frustrated Lewis Pairs

Effects of the electronic structure of five-membered N-heterocyclic carbenes on insertion of silanes and boranes into the NHC C–N bond

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Carbene‐9‐BBN Ring Expansions as a Route to Intramolecular Frustrated Lewis Pairs for CO2 Reduction

Cited by 169 publications

References 52 publications

Insertion of Group 12–16 Hydrides into NHCs: A Theoretical Investigation

Insertion of Group 12–16 Hydrides into NHCs: A Theoretical Investigation

Frustrated Lewis Pairs

Effects of the electronic structure of five-membered N-heterocyclic carbenes on insertion of silanes and boranes into the NHC C–N bond

Contact Info

Product

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Carbene‐9‐BBN Ring Expansions as a Route to Intramolecular Frustrated Lewis Pairs for CO₂ Reduction