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Ammonia Activation by a Nickel NCN‐Pincer Complex featuring a Non‐Innocent N‐Heterocyclic Carbene: Ammine and Amido Complexes in Equilibrium
Author(s) -
Brown Rudy M.,
Borau Garcia Javier,
Valjus Juuso,
Roberts Christopher J.,
Tuon Heikki M.,
Parvez Masood,
Roesler Roland
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201500453
Subject(s) - carbene , chemistry , deprotonation , pincer movement , ligand (biochemistry) , nickel , pincer ligand , medicinal chemistry , solvent , photochemistry , polymer chemistry , catalysis , organic chemistry , ion , biochemistry , receptor
A Ni 0 ‐NCN pincer complex featuring a six‐membered N‐heterocyclic carbene (NHC) central platform and amidine pendant arms was synthesized by deprotonation of its Ni II precursor. It retained chloride in the square‐planar coordination sphere of nickel and was expected to be highly susceptible to oxidative addition reactions. The Ni 0 complex rapidly activated ammonia at room temperature, in a ligand‐assisted process where the carbene carbon atom played the unprecedented role of proton acceptor. For the first time, the coordinated (ammine) and activated (amido) species were observed together in solution, in a solvent‐dependent equilibrium. A structural analysis of the Ni complexes provided insight into the highly unusual, non‐innocent behavior of the NHC ligand.