Matrix-Isolation Decay Kinetics of Triplet Cyclobutanediyls. Observation of Both Arrhenius Behavior and Heavy-Atom Tunneling in C—C Bond-Forming Reactions

Michael B. Sponsler; Rakesh Jain; Frank D. Corns; Dennis A. Dougherty

doi:10.1021/ja00188a045

Matrix-Isolation Decay Kinetics of Triplet Cyclobutanediyls. Observation of Both Arrhenius Behavior and Heavy-Atom Tunneling in C—C Bond-Forming Reactions

Michael B. Sponsler, Rakesh Jain, Frank D. Corns, Dennis A. Dougherty

Research output: Contribution to journal › Article › peer-review

57 Scopus citations

Abstract

The ring-closure reactions of a variety of triplet 1,3-cyclobutanediyls (1) have been observed by EPR spectroscopy under matrix-isolation conditions. It is shown that matrix-site effects can be very well modeled by a Gaussian distribution of activation energies with a standard deviation of ca. 0.5 kcal/mol. Several new techniques have been developed to model such dispersive kinetics. Structures 1 with delocalizing substituents (vinyl, phenyl) show conventional Arrhenius behavior, with log A = 6–8 and E_a = 1–2 kcal/mol. Fully localized cyclobutanediyls ring close via quantum mechanical tunneling. A model emphasizing the differing well depths of the singlet biradicals is developed to rationalize these contrasting behaviors.

Original language	English (US)
Pages (from-to)	2240-2252
Number of pages	13
Journal	Journal of the American Chemical Society
Volume	111
Issue number	6
DOIs	https://doi.org/10.1021/ja00188a045
State	Published - Mar 1989
Externally published	Yes

ASJC Scopus subject areas

Catalysis
General Chemistry
Biochemistry
Colloid and Surface Chemistry

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Matrix-Isolation Decay Kinetics of Triplet Cyclobutanediyls. Observation of Both Arrhenius Behavior and Heavy-Atom Tunneling in C—C Bond-Forming Reactions. / Sponsler, Michael B.; Jain, Rakesh; Corns, Frank D. et al.
In: Journal of the American Chemical Society, Vol. 111, No. 6, 03.1989, p. 2240-2252.

Research output: Contribution to journal › Article › peer-review

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abstract = "The ring-closure reactions of a variety of triplet 1,3-cyclobutanediyls (1) have been observed by EPR spectroscopy under matrix-isolation conditions. It is shown that matrix-site effects can be very well modeled by a Gaussian distribution of activation energies with a standard deviation of ca. 0.5 kcal/mol. Several new techniques have been developed to model such dispersive kinetics. Structures 1 with delocalizing substituents (vinyl, phenyl) show conventional Arrhenius behavior, with log A = 6–8 and Ea = 1–2 kcal/mol. Fully localized cyclobutanediyls ring close via quantum mechanical tunneling. A model emphasizing the differing well depths of the singlet biradicals is developed to rationalize these contrasting behaviors.",

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AU - Dougherty, Dennis A.

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Matrix-Isolation Decay Kinetics of Triplet Cyclobutanediyls. Observation of Both Arrhenius Behavior and Heavy-Atom Tunneling in C—C Bond-Forming Reactions

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