Observation of a Thermally Accessible Triplet State Resulting from Rotation around a Main-Group π Bond

Arseni Kostenko; Boris Tumanskii; Miriam Karni; Shigeyoshi Inoue; Masaaki Ichinohe; Akira Sekiguchi; Yitzhak Apeloig

doi:10.1002/anie.201506291

Observation of a Thermally Accessible Triplet State Resulting from Rotation around a Main-Group π Bond

Arseni Kostenko
, Boris Tumanskii
, Miriam Karni
, Shigeyoshi Inoue
, Masaaki Ichinohe
, Akira Sekiguchi
, Yitzhak Apeloig

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

31 Scopus citations

Abstract

We report the first direct spectroscopic observation by electron paramagnetic resonance (EPR) spectroscopy of a triplet diradical that is formed in a thermally induced rotation around a main-group π bond, that is, the Si-Si double bond of tetrakis(di-tert-butylmethylsilyl)disilene (1). The highly twisted ground-state geometry of singlet 1 allows access to the perpendicular triplet diradical 2 at moderate temperatures of 350-410 K. DFT-calculated zero-field splitting (ZFS) parameters of 2 accurately reproduce the experimentally observed half-field transition. Experiment and theory suggest a thermal equilibrium between 1 and 2 with a very low singlet-triplet energy gap of only 7.3 kcal mol^-1.

Original language	English
Pages (from-to)	12144-12148
Number of pages	5
Journal	Angewandte Chemie International Edition in English
Volume	54
Issue number	41
DOIs	https://doi.org/10.1002/anie.201506291
State	Published - 1 Oct 2015
Externally published	Yes

Keywords

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

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10.1002/anie.201506291

Cite this

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title = "Observation of a Thermally Accessible Triplet State Resulting from Rotation around a Main-Group π Bond",

abstract = "We report the first direct spectroscopic observation by electron paramagnetic resonance (EPR) spectroscopy of a triplet diradical that is formed in a thermally induced rotation around a main-group π bond, that is, the Si-Si double bond of tetrakis(di-tert-butylmethylsilyl)disilene (1). The highly twisted ground-state geometry of singlet 1 allows access to the perpendicular triplet diradical 2 at moderate temperatures of 350-410 K. DFT-calculated zero-field splitting (ZFS) parameters of 2 accurately reproduce the experimentally observed half-field transition. Experiment and theory suggest a thermal equilibrium between 1 and 2 with a very low singlet-triplet energy gap of only 7.3 kcal mol-1.",

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

author = "Arseni Kostenko and Boris Tumanskii and Miriam Karni and Shigeyoshi Inoue and Masaaki Ichinohe and Akira Sekiguchi and Yitzhak Apeloig",

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doi = "10.1002/anie.201506291",

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T1 - Observation of a Thermally Accessible Triplet State Resulting from Rotation around a Main-Group π Bond

AU - Kostenko, Arseni

AU - Tumanskii, Boris

AU - Karni, Miriam

AU - Inoue, Shigeyoshi

AU - Ichinohe, Masaaki

AU - Sekiguchi, Akira

AU - Apeloig, Yitzhak

PY - 2015/10/1

Y1 - 2015/10/1

N2 - We report the first direct spectroscopic observation by electron paramagnetic resonance (EPR) spectroscopy of a triplet diradical that is formed in a thermally induced rotation around a main-group π bond, that is, the Si-Si double bond of tetrakis(di-tert-butylmethylsilyl)disilene (1). The highly twisted ground-state geometry of singlet 1 allows access to the perpendicular triplet diradical 2 at moderate temperatures of 350-410 K. DFT-calculated zero-field splitting (ZFS) parameters of 2 accurately reproduce the experimentally observed half-field transition. Experiment and theory suggest a thermal equilibrium between 1 and 2 with a very low singlet-triplet energy gap of only 7.3 kcal mol-1.

AB - We report the first direct spectroscopic observation by electron paramagnetic resonance (EPR) spectroscopy of a triplet diradical that is formed in a thermally induced rotation around a main-group π bond, that is, the Si-Si double bond of tetrakis(di-tert-butylmethylsilyl)disilene (1). The highly twisted ground-state geometry of singlet 1 allows access to the perpendicular triplet diradical 2 at moderate temperatures of 350-410 K. DFT-calculated zero-field splitting (ZFS) parameters of 2 accurately reproduce the experimentally observed half-field transition. Experiment and theory suggest a thermal equilibrium between 1 and 2 with a very low singlet-triplet energy gap of only 7.3 kcal mol-1.

KW - EPR spectroscopy

KW - density functional calculations

KW - diradicals

KW - disilenes

KW - zero-field splitting parameters

UR - https://www.scopus.com/pages/publications/84942836612

U2 - 10.1002/anie.201506291

DO - 10.1002/anie.201506291

M3 - Article

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SN - 1433-7851

VL - 54

SP - 12144

EP - 12148

JO - Angewandte Chemie International Edition in English

JF - Angewandte Chemie International Edition in English

IS - 41

ER -

Observation of a Thermally Accessible Triplet State Resulting from Rotation around a Main-Group π Bond

Abstract

Keywords

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