6,6'-Biindeno[1,2- b]anthracene: An Open-Shell Biaryl with High Diradical Character

Xiushang Xu; Satoshi Takebayashi; Hiroki Hanayama; Serhii Vasylevskyi; Takatsugu Onishi; Tatsuhiko Ohto; Hirokazu Tada; Akimitsu Narita

doi:10.1021/jacs.2c13890

6,6'-Biindeno[1,2- b]anthracene: An Open-Shell Biaryl with High Diradical Character

J Am Chem Soc. 2023 Feb 13. doi: 10.1021/jacs.2c13890. Online ahead of print.

Authors

Xiushang Xu^{1

2}, Satoshi Takebayashi³, Hiroki Hanayama¹, Serhii Vasylevskyi⁴, Takatsugu Onishi¹, Tatsuhiko Ohto^{5

6}, Hirokazu Tada⁵, Akimitsu Narita^{1

2}

Affiliations

¹ Organic and Carbon Nanomaterials Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan.
² Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
³ Science and Technology Group, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan.
⁴ Engineering Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan.
⁵ Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
⁶ Center for Quantum Information and Quantum Biology, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.

PMID: 36780241
DOI: 10.1021/jacs.2c13890

Abstract

We report in situ generation of a 6,6'-biindeno[1,2-b]anthracene (BIA) derivative as an open-shell biaryl with high diradical character, which could be identified by mass spectrometry, NMR spectroscopy, single-crystal X-ray analysis, UV-vis-NIR absorption spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. Theoretical calculations by various methods and variable-temperature EPR analyses were performed to tackle the elusive ground state of BIA diradical, suggesting a singlet ground state with a nearly degenerate triplet state. These results provide insight into the design of unique open-shell biaryls.