Dinitrogen activation by a titanium hydride complex supported by 2-butene ligand

• Published in: Inorganic chemistry frontiers Vol. 11; no. 1; pp. 27 - 214
• Main Authors: Shi, Xianghui, Zhang, Yongliang, Zhong, Mingdong, Feng, Rui, Chen, Yuanjin, Yu, Lei, Wu, Yue, Wei, Junnian, Xi, Zhenfeng
• Format: Journal Article
• Language: English
• Published: London Royal Society of Chemistry 20.12.2023
• Subjects: Alkylidene; Ammonia; Crystallography; Hexanes; Hydrazines; Lithium hydrides; Nitrogen compounds; Reducing agents; Titanium compounds
• ISSN: 2052-1553; 2052-1545; 2052-1553
• DOI: 10.1039/d3qi01911j

The activation of dinitrogen by a titanium hydride complex with two bridging hydrides located between metal Ti and Li was investigated. Exposing cyclic bis-alkylidene titanium complex 1 to H 2 in THF solution yielded titanium hydride 2 , {[(2-butene)(C 5 H 5 )Ti](μ-H) 2 Li(THF) 3 }. 2 aggregated into dimer 3 in hexane, accompanied by the release of LiH. Treatment of 2 with N 2 (1 atm) in THF resulted in ionic end-on bridged dinitrogen dititanium complex 4 , {[((2-butene)(C 5 H 5 )Ti) 2 (μ 2 -η 1 ,η 1 -N 2 )][Li(THF) 4 ]}, without using external reducing agents. Furthermore, 4 could be oxidized to yield the binuclear complex 5 , {[(2-butene)(C 5 H 5 )Ti] 2 (μ 2 -η 1 ,η 1 -N 2 )}. The solid-state structures of 4 and 5 , as revealed by X-ray crystallographic studies, exhibit relatively short N-N bond distances of 1.198(2) Å and 1.179(2) Å, respectively. These results align with the observed N-N Raman stretching frequencies at 1699 cm −1 and 1704 cm −1 . The N 2 moiety bridging two titanium atoms could be converted into ammonia and hydrazine upon treatment with a proton source and reductant. The activation of dinitrogen by a titanium hydride complex with two bridging hydrides located between metal Ti and Li was investigated.