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Updated: Apr 10, 2026
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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
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On the tunneling instability of a hypercoordinated carbocation
1Chemistry Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel. kozuch@bgu.ac.il.
Physical Chemistry Chemical Physics : PCCP
|June 16, 2015
Summary
Pentacoordinate carbocations like C(CH3)5(+) are fleeting. Carbon tunneling prevents persistence even at 0 K, but deuterium substitution may extend their lifespan without breaking C-H bonds.
Area of Science:
- Theoretical chemistry
- Physical organic chemistry
Background:
- Pentacoordinate carbocations are transient species.
- C(CH3)5(+) was previously considered stable only at low temperatures.
Purpose of the Study:
- To investigate the persistence of C(CH3)5(+) at 0 K.
- To explore methods for extending the lifespan of pentacoordinate carbocations.
Main Methods:
- Computational theoretical methods.
- Quantum mechanical calculations to assess molecular stability.
Main Results:
- Carbon tunneling significantly reduces the persistence of C(CH3)5(+), even at absolute zero.
- Deuterium substitution is proposed as a strategy to increase molecular stability.
- The proposed stabilization occurs without altering carbon-hydrogen bonds.
Conclusions:
- C(CH3)5(+) is inherently unstable at 0 K due to quantum tunneling.
- Deuterium substitution offers a potential pathway to stabilize fleeting carbocations.
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