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 BC3four-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.
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
Lei
L
Wang
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
Yong
Y
Fang
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
Haochuan
H
Mao
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
Yi
Y
Qu
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
Jiacheng
J
Zuo
School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huai'an, 223300, P. R. China.
Zaichao
Z
Zhang
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
Gengwen
G
Tan
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
Xinping
X
Wang
DFT calculations; EPR; boron; diradical; triplet ground state