Taming Copper(I) Cyanate and Selenocyanate with N‐Heterocyclic Carbenes

Abstract

The synthesis of N‐heterocyclic carbene (NHC) adducts of copper(I) cyanate and copper(I) selenocyanate has been successfully achieved via the reaction of [Cu(NHC)Cl] with silver(I) cyanate and potassium selenocyanate respectively. Three copper(I) cyanate complexes [Cu(IXy)(NCO)] (1), [Cu(IPr)(NCO)] (2) and [Cu(SIPr)(NCO)] (3) [IXy = 1,3‐bis(2,6‐dimethylphenyl)imidazol‐2‐ylidene, IPr = 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene, SIPr = 1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene] have been prepared and fully characterised. The X‐ray crystal structures reveal the three complexes to be monomeric species in which the cyanate ligand is end‐on, N‐bound. These complexes, represent the first examples of monomeric copper(I) cyanate complexes. In addition, the copper(I) selenocyanate species [Cu(IPr)(NCSe)]2 (4) was prepared and fully characterised. The X‐ray crystal structure reveals that a centrosymmetric dimer is formed with bridging selenocyanate ligands bound through both N and Se. This is in contrast to the monomeric structure observed in the previously reported and related complex [Cu(IPr)(NCS)]. Complex 4 represents a rare example of a stable dimeric adduct of copper(I) selenocyanate.