The unusual quadruple bonding of nitrogen in ThN

Zejie Fei; Jia-Qi Wang; Rulin Tang; Yuzhu Lu; Changcai Han; Yongtian Wang; Jing Hong; Changwu Dong; Han-Shi Hu; Xiao-Gen Xiong; Chuangang Ning; Hongtao Liu; Jun Li

doi:10.1038/s41467-023-43208-z

The unusual quadruple bonding of nitrogen in ThN

Nat Commun. 2023 Nov 24;14(1):7677. doi: 10.1038/s41467-023-43208-z.

Authors

Zejie Fei^#¹, Jia-Qi Wang^#^{2

3}, Rulin Tang⁴, Yuzhu Lu⁴, Changcai Han¹, Yongtian Wang¹, Jing Hong^{1

5}, Changwu Dong¹, Han-Shi Hu², Xiao-Gen Xiong⁶, Chuangang Ning⁷, Hongtao Liu⁸, Jun Li²

Affiliations

¹ Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, China.
² Department of Chemistry, Tsinghua University, Beijing, 100084, China.
³ College of Science, Beijing Forestry University, Beijing, 100083, China.
⁴ Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Collaborative Innovation Center of Quantum Matter, Tsinghua University, Beijing, 100084, China.
⁵ University of Chinese Academy of Sciences, Beijing, 100049, China.
⁶ Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai, 519082, China. xiongxg@mail.sysu.edu.cn.
⁷ Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Collaborative Innovation Center of Quantum Matter, Tsinghua University, Beijing, 100084, China. ningcg@tsinghua.edu.cn.
⁸ Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, China. liuhongtao@sinap.ac.cn.

^# Contributed equally.

Abstract

Nitrogen has five valence electrons and can form a maximum of three shared electron-pair bonds to complete its octet, which suggests that its maximum bond order is three. With a joint anion photoelectron spectroscopy and quantum chemistry investigation, we report herein that nitrogen presents a quadruple bonding interaction with thorium in ThN. The quadruple Th≣N bond consists of two electron-sharing Th-N π bonds formed between the Th-6d_xz/6d_yz and N 2p_x/2p_y orbitals, one dative Th←N σ bond and one weak Th←N σ bonding interaction formed between Th-6d_z² and N 2s/2p_z orbitals. The ThC molecule has also been investigated and proven to have a similar bonding pattern as ThN. Nonetheless, due to one singly occupied σ-bond, ThC is assigned a bond order of 3.5. Moreover, ThC has a longer bond length as well as a lower vibrational frequency in comparison with ThN.

Abstract

Grants and funding