Ligand Protonation Triggers H 2 Release from a Dinickel Dihydride Complex to Give a Doubly “T”‐Shaped Dinickel(I) Metallodiradical

作者：Peng‐Cheng Duan, Roland A. Schulz, Anton Römer, Benjamin E. Van Kuiken, Sebastian Dechert, Serhiy Demeshko, George E. Cutsail, Serena DeBeer, Ricardo A. Mata, Franc Meyer · 发表于：Angewandte Chemie International Edition · 年份：2020 · DOI：10.1002/anie.202011494 · 被引用次数：22 · 研究领域：Magnetism in coordination complexes、Metal-Organic Frameworks: Synthesis and Applications、Metalloenzymes and iron-sulfur proteins

Abstract The dinickel(II) dihydride complex ( 1 K ) of a pyrazolate‐based compartmental ligand with β‐diketiminato (nacnac) chelate arms (L − ), providing two pincer‐type {N 3 } binding pockets, has been reported to readily eliminate H 2 and to serve as a masked dinickel(I) species. Discrete dinickel(I) complexes ( 2 Na , 2 K ) of L − are now synthesized via a direct reduction route. They feature two adjacent T‐shaped metalloradicals that are antiferromagnetically coupled, giving an S =0 ground state. The two singly occupied local type magnetic orbitals are oriented into the bimetallic cleft, enabling metal–metal cooperative 2 e − substrate reductions as shown by the rapid reaction with H 2 or O 2 . X‐ray crystallography reveals distinctly different positions of the K + in 1 K and 2 K , suggesting a stabilizing interaction of K + with the dihydride unit in 1 K . H 2 release from 1 K is triggered by peripheral γ‐C protonation at the nacnac subunits, which DFT calculations show lowers the barrier for reductive H 2 elimination from the bimetallic cleft.