An Isolable Diboron‐Centered Diradical with a Triplet Ground State

Two new diboranes, 2,6‐bis(BMes2)mesitylene (1) and 3,3′‐bis(BMes2)bimesitylene (3), were synthesized. Two‐electron reduction of 1 with elemental potassium afforded the C−H activation product [(18‐c‐6)K(THF)2]2+⋅22− bearing a BC3 four‐membered ring as colorless crystals, whereas the reduction of 3 w...

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Bibliographic Details
Published in:Chemistry : a European journal 2017-05, Vol.23 (28), p.6930-6936
Main Authors: Wang, Lei, Fang, Yong, Mao, Haochuan, Qu, Yi, Zuo, Jiacheng, Zhang, Zaichao, Tan, Gengwen, Wang, Xinping
Format: Article
Language:English
Subjects:
Boron
Chemistry
Crystal structure
Crystals
DFT calculations
diradical
Electron paramagnetic resonance
Electron spin
Electron spin resonance
EPR
Ground state
Helium
Mathematical analysis
Mesitylene
Potassium
Reduction
Spectroscopy
Superconducting quantum interference devices
triplet ground state
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Summary:Two new diboranes, 2,6‐bis(BMes2)mesitylene (1) and 3,3′‐bis(BMes2)bimesitylene (3), were synthesized. Two‐electron reduction of 1 with elemental potassium afforded the C−H activation product [(18‐c‐6)K(THF)2]2+⋅22− bearing a BC3 four‐membered ring as colorless crystals, whereas the reduction of 3 with potassium led to the isolation of [(18‐c‐6)K(THF)2]2+⋅32−.. as dark blue crystals. Both reduction products were characterized by structural and spectroscopic methods. Electron paramagnetic resonance (EPR) spectroscopy and theoretical calculations revealed that the electron spin density of 32−.. mainly resides on the two boron nuclei and features a triplet ground state, which was confirmed by superconducting quantum interference device (SQUID) measurements as well as theoretical calculations. 32−.. represents the first structurally characterized boron‐centered diradical with a triplet ground state. In addition, the reactivity of [(18‐c‐6)K(THF)2]2+⋅32−.. toward PhSeSePh and nBu3SnH was investigated, which is consistent with its radical character. Stable Diradical: A diboron diradical featuring a triplet ground state is isolated and fully characterized by single‐crystal X‐Ray diffraction, electron paramagnetic resonance spectroscopy, and UV/Vis spectroscopy, as well as superconducting quantum interference device (SQUID) measurements, in conjunction with DFT calculations. In addition, its reactivity is investigated.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201701308