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Updated: Feb 19, 2026

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
A hybrid imidazolylidene/imidazolium nickel NHC complex: an isolated intermediate
Philipp J Altmann1, Michael Ehrenreich1, Alexander Pöthig1
1Catalysis Research Center & Department of Chemistry, Technische Universität München, Ernst-Otto-Fischer-Strasse 1, D-85747 Garching, Germany.
Abstract:
Macrocyclic ligand systems with a variety of (different) donor sites oftentimes give rise to very exciting and unexpected multinuclear metal complexes. We report herein the structure of a trinuclear mixed imidazolylidene/imidazolium nickel N-heterocyclic carbene (NHC) complex, namely di-μ-chlorido-bis{μ-calix[2]imidazolium[2]imidazolylidene[2]pyrazolate}trinickel(II) tetrakis(hexafluoridophosphate) acetonitrile tetrasolvate, [Ni3(C24H24N12)2Cl2](PF6)4·4CH3CN or [Ni3(LMe)2Cl2](PF6)4·4CH3CN, that can be understood as a trapped reaction intermediate during the synthesis of the respective [Ni2LMe](PF6)2 product. The structure not only contains protonated next to deprotonated imidazole heterocycles, but also Ni2+ ions with fundamentally different coordination modes within one molecule. Two of the three metal atoms are coordinated in a square-pyramidal fashion by half a ligand molecule and one chloride ligand, whereas the third Ni2+ ion is bound octahedrally by four pyrazolate moieties and two chloride anions.
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