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Merging Pincer Motifs and Potential Metal–Metal Cooperativity in Cobalt Dinitrogen Chemistry: Efficient Catalytic Silylation of N 2 to N(SiMe 3 ) 3
Author(s) -
Li Ming,
Gupta Sandeep K.,
Dechert Sebastian,
Demeshko Serhiy,
Meyer Franc
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202101387
Subject(s) - chemistry , pincer ligand , catalysis , protonation , deprotonation , ligand (biochemistry) , bimetallic strip , trifluoromethanesulfonate , silylation , pincer movement , bridging ligand , cooperativity , cobalt , metal , stereochemistry , combinatorial chemistry , medicinal chemistry , inorganic chemistry , organic chemistry , biochemistry , ion , receptor
Using a pyrazolate‐bridged dinucleating ligand that provides two proximate pincer‐type PNN binding sites (“two‐in‐one pincer”), different synthetic routes have been developed towards its dicobalt(I) complex 2 that features a twice deprotonated ligand backbone and two weakly activated terminal N 2 substrate ligands directed into the bimetallic pocket. Protonation of 2 is shown to occur at the ligand scaffold and to trigger conversion to a tetracobalt(I) complex 4 with two end‐on μ 1,2 ‐bridging N 2 ; in THF 4 is labile and undergoes temperature‐dependent N 2 /triflate ligand exchange. These pyrazolate‐based systems combine the potential of exhibiting both metal–metal and metal–ligand cooperativity, viz. two concepts that have emerged as promising design motifs for molecular N 2 fixation catalysts. Complex 2 serves as an efficient (pre)catalyst for the reductive silylation of N 2 into N(SiMe 3 ) 3 (using KC 8 and Me 3 SiCl), yielding up to 240 equiv N(SiMe 3 ) 3 per catalyst.