First aryl-substituted acyclic imino-N-heterocyclic carbene ligand precursor: synthesis, characterisation and coordination with silver(i) and copper(i)

Abstract

The first aryl-substituted imino-N-heterocyclic ligand precursor was prepared and structurally characterised, along with the corresponding silver(i) and copper(i) chloride complexes. An unusual T-shape coordination mode for the copper centre was observed.

Structural Diversity of Copper(I)–N‐Heterocyclic Carbene Complexes; Ligand Tuning Facilitates Isolation of the First Structurally Characterised Copper(I)–NHC Containing a Copper(I)–Alkene Interaction

“…This type of complex has been observed previously in only two other examples. [21,33] The structure is somewhat unexpected, especially given that elemental analysis gives a ratio of 1:1 NHC:CuBr. Due to the labile nature of copper(I)-NHCs, it is possible that transmetallation occurs during crystallisation giving 1 mole equivalent of the Cu(NHC) 2 Br and 1 mole equivalent of CuBr.…”

“…[33] The copper(I) centre in complex 2e is 2-coordinate with an approximately linear geometry (172.1°) ( Figure 5). …”

N‐Heterocyclic Carbenes and Imidazole‐2‐thiones as Ligands for the Gold(I)‐Catalysed Hydroamination of Phenylacetylene

“…Although much less common in gold complexes, [30] similar ligand exchange reactions in related silver halide complexes have been well documented [31] and have been the subject of a recent study by Bergbreiter et al [32] This hypothesis was further validated through the synthesis of the gold complex of 1-[1- www.chemeurj.org pound 1. The reaction of [(C^Imine Me )AgCl] (8) [20] with [AuA C H T U N G T R E N N U N G (SMe 2 )Cl] gave [(C^Imine Me )AuCl] (9) cleanly in 85 % yield (Scheme 4). Multiple attempts to prepare the free carbene for subsequent use in the preparation of compound 9 only led to multiple decomposition products due to competing deprotonation of the iminic methyl group.…”

“…The C4 À N3 bond measures 1.259(7) , a value that is consistent with the C=N stretching frequency and similar to that observed in the isostructural starting silver complex. [20] The solid-state structure of 9 suggests that compound 6 is indeed formed upon addition of C^Imine tBu…”

“…[17] As such, many groups, including ours, have reported complexes with het-A C H T U N G T R E N N U N G eroditopic NHC ligands that contain a carbene and a covalently attached nitrogen donor, such as a pyridine, an oxazoline and an imine group. [18][19][20][21] Although several gold complexes of simple carbenes have been reported and used in many catalytic reactions, [3, 5, 6, 8-13, 16, 22-24] very little work has been reported on hydroamination by using heteroditopic NHC gold(I) complexes. [25] We, therefore, became interested in studying gold(I) complexes of N-heterocyclic carbene ligands that contain a pendent imine group as potential hemilabile donors in hydroamination catalysis.…”