N‐Heterocyclic Carbene Complexes of Copper(I) Thiocyanate: Synthesis and Structural Characterization

Abstract

AbstractThe synthesis and characterization of three N‐heterocyclic carbene (NHC) complexes of copper(I) thiocyanate [Cu(IMes)(NCS)]2 (1), [Cu(IXy)(NCS)]2 (2), and [Cu(IPr)(NCS)] (3) [IMes = 1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene, IXy = 1,3‐bis(2,6‐dimethylphenyl)imidazol‐2‐ylidene, IPr = 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene] are described. Single crystal diffraction and IR spectroscopy shows that reaction of one equivalent of sodium thiocyanate with [Cu(NHC)Cl] results in the formation of solid‐state centrosymmetric dimers for 1 and 2 with bridging thiocyanate ligands bound through both N and S. In contrast, the equivalent reaction with IPr gives a monomeric species with N bound thiocyanate. In the solution state, all the structures of complexes 1–3 would appear to be monomeric, as evidenced by both solution state FT‐IR and 13C NMR spectroscopic studies. In addition the precursor to complex 2 [Cu(IXy)Cl] (4) was structurally characterized by X‐ray diffraction revealing a one‐dimensional chain structure that propagates through C–H···Cl intermolecular interactions with both methyl and aromatic hydrogen atoms.