Spectroscopic Observation of the Triplet Diradical State of a Cyclobutadiene

Arseni Kostenko; Boris Tumanskii; Yuzuru Kobayashi; Masaaki Nakamoto; Akira Sekiguchi; Yitzhak Apeloig

doi:10.1002/anie.201705228

Spectroscopic Observation of the Triplet Diradical State of a Cyclobutadiene

Arseni Kostenko, Boris Tumanskii, Yuzuru Kobayashi, Masaaki Nakamoto, Akira Sekiguchi, Yitzhak Apeloig

Technion - Israel Institute of Technology

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

Abstract

Tetrakis(trimethylsilyl)cyclobuta-1,3-diene (1) was subjected to a temperature-dependent EPR study to allow the first spectroscopic observation of a triplet diradical state of a cyclobutadiene (2). From the temperature dependent EPR absorption area we derive a singlet→triplet (1→2) energy gap, E_ST, of 13.9 kcal mol⁻¹, in agreement with calculated values. The zero-field splitting parameters D=0.171 cm⁻¹, E=0 cm⁻¹ are accurately reproduced by DFT calculations. The triplet diradical 2 is thermally accessible at moderate temperatures. It is not an intermediate in the thermal cycloreversion of cyclobutadiene to two acetylene molecules.

Original language	English
Pages (from-to)	10183-10187
Number of pages	5
Journal	Angewandte Chemie - International Edition
Volume	56
Issue number	34
DOIs	https://doi.org/10.1002/anie.201705228
State	Published - 14 Aug 2017

Keywords

EPR spectroscopy
cyclobutadiene
density functional calculations
diradicals
zero-field splitting parameters

All Science Journal Classification (ASJC) codes

Catalysis
General Chemistry

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10.1002/anie.201705228

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title = "Spectroscopic Observation of the Triplet Diradical State of a Cyclobutadiene",

abstract = "Tetrakis(trimethylsilyl)cyclobuta-1,3-diene (1) was subjected to a temperature-dependent EPR study to allow the first spectroscopic observation of a triplet diradical state of a cyclobutadiene (2). From the temperature dependent EPR absorption area we derive a singlet→triplet (1→2) energy gap, EST, of 13.9 kcal mol−1, in agreement with calculated values. The zero-field splitting parameters D=0.171 cm−1, E=0 cm−1 are accurately reproduced by DFT calculations. The triplet diradical 2 is thermally accessible at moderate temperatures. It is not an intermediate in the thermal cycloreversion of cyclobutadiene to two acetylene molecules.",

keywords = "EPR spectroscopy, cyclobutadiene, density functional calculations, diradicals, zero-field splitting parameters",

author = "Arseni Kostenko and Boris Tumanskii and Yuzuru Kobayashi and Masaaki Nakamoto and Akira Sekiguchi and Yitzhak Apeloig",

note = "Publisher Copyright: {\textcopyright} 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim",

year = "2017",

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doi = "10.1002/anie.201705228",

language = "الإنجليزيّة",

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T1 - Spectroscopic Observation of the Triplet Diradical State of a Cyclobutadiene

AU - Kostenko, Arseni

AU - Tumanskii, Boris

AU - Kobayashi, Yuzuru

AU - Nakamoto, Masaaki

AU - Sekiguchi, Akira

AU - Apeloig, Yitzhak

PY - 2017/8/14

Y1 - 2017/8/14

N2 - Tetrakis(trimethylsilyl)cyclobuta-1,3-diene (1) was subjected to a temperature-dependent EPR study to allow the first spectroscopic observation of a triplet diradical state of a cyclobutadiene (2). From the temperature dependent EPR absorption area we derive a singlet→triplet (1→2) energy gap, EST, of 13.9 kcal mol−1, in agreement with calculated values. The zero-field splitting parameters D=0.171 cm−1, E=0 cm−1 are accurately reproduced by DFT calculations. The triplet diradical 2 is thermally accessible at moderate temperatures. It is not an intermediate in the thermal cycloreversion of cyclobutadiene to two acetylene molecules.

AB - Tetrakis(trimethylsilyl)cyclobuta-1,3-diene (1) was subjected to a temperature-dependent EPR study to allow the first spectroscopic observation of a triplet diradical state of a cyclobutadiene (2). From the temperature dependent EPR absorption area we derive a singlet→triplet (1→2) energy gap, EST, of 13.9 kcal mol−1, in agreement with calculated values. The zero-field splitting parameters D=0.171 cm−1, E=0 cm−1 are accurately reproduced by DFT calculations. The triplet diradical 2 is thermally accessible at moderate temperatures. It is not an intermediate in the thermal cycloreversion of cyclobutadiene to two acetylene molecules.

KW - EPR spectroscopy

KW - cyclobutadiene

KW - density functional calculations

KW - diradicals

KW - zero-field splitting parameters

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DO - 10.1002/anie.201705228

M3 - مقالة

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SN - 1433-7851

VL - 56

SP - 10183

EP - 10187

JO - Angewandte Chemie - International Edition

JF - Angewandte Chemie - International Edition

IS - 34

ER -

Spectroscopic Observation of the Triplet Diradical State of a Cyclobutadiene

Abstract

Keywords

All Science Journal Classification (ASJC) codes

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