Bypassing a highly unstable frustrated Lewis pair: dihydrogen cleavage by a thermally robust silylium–phosphine adduct

Herrington, Thomas J.; Ward, Bryan J.; Doyle, Laurence R.; McDermott, Joe; White, Andrew J. P.; Hunt, Patricia A.; Ashley, Andrew E.

doi:10.1039/c4cc05905k

Cited by 80 publications

(62 citation statements)

References 39 publications

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“…[86][87] In related work, Ashley et al 88 showed that silylium-phosphine adducts activate H 2 under elevated temperatures, presumably via the thermal generation of an FLP. Müller and co-workers 89 also developed a silylene/silylium FLP (Scheme 5), demonstrating that it too activates H 2 although the protonated silylene rearranges to a hydrogen-bridged disilyl cation.…”

Section: Silicon-based Flpsmentioning

confidence: 98%

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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Section: Silicon-based Flpsmentioning

confidence: 98%

Frustrated Lewis Pairs

2015

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“…38 Further, Ashley et al reported on a phosphine stabilized silylium species able to cleave H 2 . 39 We report herein the formation of novel intramolecular FLP-CO 2 adducts by reaction of CO 2 with nitrogen stabilized silyl cations. These systems exhibit excellent catalytic activity in the hydroboration of CO 2 , and the catalytic involvement of FLP-CO 2 adducts is addressed, based on mechanistic experimental, and DFT investigations (Scheme 1).…”

Section: ■ Introductionmentioning

confidence: 99%

Implications of CO₂ Activation by Frustrated Lewis Pairs in the Catalytic Hydroboration of CO₂: A View Using N/Si⁺ Frustrated Lewis Pairs

et al. 2016

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A series of base-stabilized silylium species were synthesized and their reactivity toward CO 2 explored, yielding the characterization of a novel N/ Si + FLP-CO 2 adduct. These silicon species are active catalysts in the hydroboration of CO 2 to the methoxide level with 9-BBN, catecholborane (catBH), and pinacolborane (pinBH). Both experiments and DFT calculations highlight the role of the FLP-CO 2 adduct in the catalysis. Depending on the nature of the hydroborane reductant, two distinct mechanisms have been unveiled. While 9-BBN and catBH are able to reduce an intermediate FLP-CO 2 adduct, the hydroboration of CO 2 with pinBH follows a different and novel path where the B−H bond is activated by the silicon-based Lewis acid catalyst. In these mechanisms, the formation of a highly stabilized FLP-CO 2 adduct is found detrimental to the kinetics of the reaction.

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“…As we know that a FLP contains both Lewis acid and base centers, and the most common active Lewis pairs are B/N, B/P, Al/N and Al/P. Furthermore, a cationic Lewis acid component has also been extended to silicon1516, carbon17, in ref. 9 and even the transition-metal (Zr1819 and Ti20) complexes, while the Lewis base component has been extended to O 9 , carbenes21, ethers22, ketones23, and sulfides24.…”

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confidence: 99%

Be12O12 Nano-cage as a Promising Catalyst for CO2 Hydrogenation

Zhu

et al. 2017

Sci Rep

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An efficient conversion of CO2 into valuable fuels and chemicals has been hotly pursued recently. Here, for the first time, we have explored a series of M12x12 nano-cages (M = B, Al, Be, Mg; X = N, P, O) for catalysis of CO2 to HCOOH. Two steps are identified in the hydrogenation process, namely, H2 activation to 2H*, and then 2H* transfer to CO2 forming HCOOH, where the barriers of two H* transfer are lower than that of the H2 activation reaction. Among the studied cages, Be12O12 is found to have the lowest barrier in the whole reaction process, showing two kinds of reaction mechanisms for 2H* (simultaneous transfer and a step-wise transfer with a quite low barrier). Moreover, the H2 activation energy barrier can be further reduced by introducing Al, Ga, Li, and Na to B12N12 cage. This study would provide some new ideas for the design of efficient cluster catalysts for CO2 reduction.

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Bypassing a highly unstable frustrated Lewis pair: dihydrogen cleavage by a thermally robust silylium–phosphine adduct

Cited by 80 publications

References 39 publications

Frustrated Lewis Pairs

Frustrated Lewis Pairs

Implications of CO₂ Activation by Frustrated Lewis Pairs in the Catalytic Hydroboration of CO₂: A View Using N/Si⁺ Frustrated Lewis Pairs

Be12O12 Nano-cage as a Promising Catalyst for CO2 Hydrogenation

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Bypassing a highly unstable frustrated Lewis pair: dihydrogen cleavage by a thermally robust silylium–phosphine adduct

Cited by 80 publications

References 39 publications

Frustrated Lewis Pairs

Frustrated Lewis Pairs

Implications of CO2 Activation by Frustrated Lewis Pairs in the Catalytic Hydroboration of CO2: A View Using N/Si+ Frustrated Lewis Pairs

Be12O12 Nano-cage as a Promising Catalyst for CO2 Hydrogenation

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Implications of CO₂ Activation by Frustrated Lewis Pairs in the Catalytic Hydroboration of CO₂: A View Using N/Si⁺ Frustrated Lewis Pairs