A Triply Negatively Charged Nanographene Bilayer with Spin Frustration
Wenqing Wang, Xiao‐Hui Ma, Min Liu, Shuxuan Tang, Xuguang Ding, Yue Zhao, Yuan‐Zhi Tan, Miklós Kertész, Xinping Wang
Abstract
Abstract We report on the largest open‐shell graphenic bilayer and also the first example of triply negatively charged radical π‐dimer. Upon three‐electron reduction, bilayer nanographene fragment molecule (C 96 H 24 Ar 6 ) 2 (Ar=2,6‐dimethylphenyl) ( 1 2 ) was transformed to a triply negatively charged species 1 2 3.− , which has been characterized by single‐crystal X‐ray diffraction, electron paramagnetic resonance (EPR) spectroscopy and magnetic properties on a superconducting quantum interference device (SQUID). 1 2 3.− features a 96‐center‐3‐electron (96 c /3 e ) pancake bond with a doublet ground state, which can be thermally excited to a quartet state. It consists of 34 π‐fused rings with 96 conjugated sp 2 carbon atoms. Spin frustration is observed with the frustration parameter f >31.8 at low temperatures in 1 2 3.− , which indicates graphene upon reduction doping may behave as a quantum spin liquid.