Reactions that involve tunneling by carbon and the role that calculations have played in their study

Borden, Weston Thatcher

doi:10.1002/wcms.1235

Cited by 108 publications

(147 citation statements)

References 94 publications

(311 reference statements)

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“…Forexample,heavy-atom tunneling is prominent in the Cope rearrangement of semibullvalene [276] and the ring-opening reaction of cyclopropylcarbinyl radicals. [277][278][279][280][281] In the former case, 12 C/ 13 CKIEs of more than 5at40Kare predicted. [276] In the latter case,t he reaction rate is nearly constant below 20 K. [279] Angewandte Chemie Reviews 3.6.…”

Section: Tunneling Of Heavy Atomsmentioning

confidence: 89%

“…[5] Thetunnel effect and its relevance for chemistry has been covered in many reviews and even textbooks over the last century.The original reference work is probably the textbook by Bell, [6] with other books and reviews following it. [7][8][9][10][11][12] Further review articles deal with special aspects,s uch as atom tunneling in enzymes [13][14][15] or methods to calculate tunneling rates. [16][17][18][19] Of course,q uantum effects such as Jan Meisner obtained his master's degree in chemistry from the University of Stuttgart.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Atom Tunneling in Chemistry

2016

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Quantum mechanical tunneling of atoms is increasingly found to play an important role in many chemical transformations. Experimentally, atom tunneling can be indirectly detected by temperature-independent rate constants at low temperature or by enhanced kinetic isotope effects. In contrast, the influence of tunneling on the reaction rates can be monitored directly through computational investigations. The tunnel effect, for example, changes reaction paths and branching ratios, enables chemical reactions in an astrochemical environment that would be impossible by thermal transition, and influences biochemical processes.

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Section: Tunneling Of Heavy Atomsmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Atom Tunneling in Chemistry

2016

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“…[23] Ther eaction of 22 just described in Scheme 6t akes place by carbon-atom tunneling. [24] Another example of heavy-atom tunneling is given by the ring expansion of chlorocarbene 23 a and fluorocarbene 23 b at 8K[Eq. (3)].…”

Section: Tunneling In Carbenesmentioning

confidence: 99%

Carbenes and Nitrenes: Recent Developments in Fundamental Chemistry

Wentrup

2018

Angew Chem Int Ed

127

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Carbenes and nitrenes can exist in both singlet and triplet states, sometimes equally stable and interconverting either thermally or photochemically. Many carbene and nitrene reactions proceed via tunneling at low temperatures. Numerous singlet and triplet states have been characterized spectroscopically, and a detailed understanding of the chemical and physical properties of carbenes and nitrenes is emerging. There has been significant progress in the direct observation of carbenes, nitrenes, and many other reactive intermediates in recent years through the application of matrix photolysis and flash vacuum pyrolysis linked with matrix isolation at cryogenic temperatures. Our understanding of singlet and triplet states has improved through the interplay of spectroscopy and computations. Bistable carbenes and nitrenes as well as many examples of tunneling have been discovered and numerous rearrangements and fragmentations have been documented. The correlation of the zero-field splitting parameter D with calculated spin densities on nitrenes and carbenes is discussed. This Minireview gives an overview of some of these developments.

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“…[18][19][20] These examples share the common criteria for as wift carbon QMT:r elatively low activation energies ande xceptionally narrow barrier widths. [24] Considering this, can the unprecedented cyclo [18]carbon undergo similar automerization by at unneling mechanism?I fs o, then C 18 may enter into the recordsa st he highest number of atoms predicted to tunnel simultaneously( most probably the current record is for [16]annulene, [19] but we are currently studying the aromatic [18]annulene as well).…”

mentioning

confidence: 99%