Unusual Hydrogenation Reactivities of a Thiolate-Bridged Dicobalt μ-Nitride Featuring a Bent {CoIII-N-CoIII} Core

Tao Mei; Peng Zhang; Zihe Song; Baomin Wang; Jingping Qu; Shengfa Ye; Dawei Yang

doi:10.1021/jacs.3c07254

Unusual Hydrogenation Reactivities of a Thiolate-Bridged Dicobalt μ-Nitride Featuring a Bent {Co^III-N-Co^III} Core

J Am Chem Soc. 2023 Sep 20;145(37):20578-20587. doi: 10.1021/jacs.3c07254. Epub 2023 Sep 6.

Authors

Tao Mei¹, Peng Zhang^{2

3}, Zihe Song¹, Baomin Wang¹, Jingping Qu^{1

4}, Shengfa Ye², Dawei Yang¹

Affiliations

¹ State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, P. R. China.
² State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China.
³ University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
⁴ State Key Laboratory of Bioreactor Engineering, Collaborative Innovation Centre for Biomanufacturing, Frontiers Science Center for Materiobiology and Dynamic Chemistry, East China University of Science and Technology, Shanghai 200237, P. R. China.

PMID: 37674257
DOI: 10.1021/jacs.3c07254

Abstract

Transition metal nitrides have received considerable attention owing to their crucial roles in nitrogen fixation and nitrogen atom transfer reactions. Compared to the early and middle transition metals, it is much more challenging to access late transition metal nitrides, especially cobalt in group 9. So far, only a handful of cobalt nitrides have been reported; consequently, their hydrogenation reactivity is largely unexplored. Herein, we present a structurally and spectroscopically well-characterized thiolate-bridged dicobalt μ-nitride [Cp*Co^III(μ-SAd)(μ-N)Co^IIICp*] (2) featuring a bent {Co^III(μ-N)Co^III} core. Remarkably, complex 2 can realize not only direct hydrogenation of nitride to amide but also stepwise N-H bond formation from nitride to ammonia. Specifically, 2 can facilely activate dihydrogen (H₂) at mild conditions to generate a dicobalt μ-amide [Cp*Co^II(μ-SAd)(μ-NH₂)Co^IICp*] (4) via an unusual mechanism of two-electron oxidation of H₂ as proposed by computational studies; in the presence of protons (H⁺) and electrons, nitride 2 can convert to dicobalt μ-imide [Cp*Co^III(μ-SAd)(μ-NH)Co^IIICp*][BPh₄] (3[BPh₄]) and to Co^IICo^II μ-amide 4, and finally release ammonia. In contrast to 2, the only other structurally characterized dicobalt μ-nitride Na(THF)₄{[(^ketguan)Co^III(N₃)]₂(μ-N)} (^ketguan = [(^tBu₂CN)C(NDipp)₂]^-, Dipp = 2,6-diisopropylphenyl) (e) that possesses a linear {Co^III(μ-N)Co^III} moiety cannot directly react with H₂ or H⁺. Further in-depth electronic structure analyses shed light on how the varying geometries of the {Co^III(μ-N)Co^III} moieties in 2 and e, bent vs linear, impart their disparate reactivities.