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 journalArticlepeer-review

28 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 languageEnglish
Pages (from-to)12144-12148
Number of pages5
JournalAngewandte Chemie International Edition in English
Volume54
Issue number41
DOIs
StatePublished - 1 Oct 2015
Externally publishedYes

Keywords

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

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