An improved protocol for the synthesis of [Au(NHC)X] (X = Cl, Br, I) complexes is reported. This versatile one-step synthetic methodology proceeds under mild conditions, in air, using technical grade solvents, is scalable and is applicable to a wide range of imidazolium and imidazolidinium salts.

A series of complexes of the type [Cu(X)(NHC)] (X = I, Br, Cl, NHC = N-heterocyclic carbene) was synthesised using a one-pot, mild and user-friendly (aerobic, tech. grade solvents) procedure.

A straightforward and scalable eight‐step synthesis of new N‐heterocyclic carbenes (NHCs) has been developed from inexpensive and readily available 2‐nitro‐m‐xylene. This process allows for the preparation of a novel class of NHCs coined ITent (“Tent” for “tentacular”) of which the well‐known IMes (N,N′‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene), IPr (N,N′‐bis(2,6‐di(2‐propyl)phenyl)imidazol‐2‐ylidene) and IPent (N,N′‐bis(2,6‐di(3‐pentyl)phenyl)imidazol‐2‐ylidene) NHCs are the simplest and already known congeners. The synthetic route was successfully used for the preparation of three members of the ITent family: IPent (N,N′‐bis(2,6‐di(3‐pentyl)phenyl)imidazol‐2‐ylidene), IHept (N,N′‐bis(2,6‐di(4‐heptyl)phenyl)imidazol‐2‐ylidene) and INon (N,N′‐bis(2,6‐di(5‐nonyl)phenyl)imidazol‐2‐ylidene). The electronic and steric properties of each NHC were studied through the preparation of both nickel and palladium complexes. Finally the effect of these new ITent ligands in Pd‐catalyzed Suzuki–Miyaura and Buchwald–Hartwig cross‐couplings was investigated.

The effect of methoxy functionalization of three N-heterocyclic carbene ligands was assessed using a variety of methods. The steric environment of each carbene has been assessed in various coordination environments. The electronic properties, specifically the electron-donating character and πaccepting ability, have been evaluated using nickel and iridium complexes and selenium adducts, respectively. Comparisons with the parent systems have been made with respect to both electronic and steric properties. The carbenes IPr OMe , SIPr OMe , and IPr* OMe have been found to be more electron donating than the parent systems IPr, SIPr, and IPr* and only slightly less π accepting, yet they exhibit similar steric properties.

This review considers phosphine and N-heterocyclic carbene complexes of gold­(I) that are used as (pre)­catalysts for a range of reactions in organic synthesis. These are divided according to the structure of the ligand, with the narrative focusing on studies that offer a quantitative comparison between the ligands and readily available or widely used existing systems.