Octa-coordinated alkaline earth metal-dinitrogen complexes M(N2)8 (M=Ca, Sr, Ba)

Qian Wang; Sudip Pan; Shujun Lei; Jiaye Jin; Guohai Deng; Guanjun Wang; Lili Zhao; Mingfei Zhou; Gernot Frenking

doi:10.1038/s41467-019-11323-5

Octa-coordinated alkaline earth metal-dinitrogen complexes M(N₂)₈ (M=Ca, Sr, Ba)

Nat Commun. 2019 Jul 29;10(1):3375. doi: 10.1038/s41467-019-11323-5.

Authors

Qian Wang¹, Sudip Pan², Shujun Lei¹, Jiaye Jin¹, Guohai Deng¹, Guanjun Wang¹, Lili Zhao², Mingfei Zhou³, Gernot Frenking^{4

5}

Affiliations

¹ Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysts and Innovative Materials, Fudan University, Shanghai, 200433, China.
² Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China.
³ Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysts and Innovative Materials, Fudan University, Shanghai, 200433, China. mfzhou@fudan.edu.cn.
⁴ Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China. frenking@chemie.uni-marburg.de.
⁵ Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, D-35043, Marburg, Germany. frenking@chemie.uni-marburg.de.

Abstract

We report the isolation and spectroscopic identification of the eight-coordinated alkaline earth metal-dinitrogen complexes M(N₂)₈ (M=Ca, Sr, Ba) possessing cubic (O_h) symmetry in a low-temperature neon matrix. The analysis of the electronic structure reveals that the metal-N₂ bonds are mainly due to [M(d_π)]→(N₂)₈ π backdonation, which explains the observed large red-shift in N-N stretching frequencies. The adducts M(N₂)₈ have a triplet (³A_1g) electronic ground state and exhibit typical bonding features of transition metal complexes obeying the 18-electron rule. We also report the isolation and bonding analysis of the charged dinitrogen complexes [M(N₂)₈]⁺ (M=Ca, Sr).