A new N-heterocyclic ligand IPr*OMe [N,N′-bis­(2,6-bis­(diphenylmethyl)-4-methoxyphenyl)­imidazol-2-ylidene] has been synthesized and compared with its earlier methyl-substituted congener IPr* [N,N′-bis­(2,6-bis­(diphenylmethyl)-4-methylphenyl)­imidazol-2-ylidene]. IPr*OMe was successfully bound to palladium, and the catalytic activity of the resulting complex [Pd­(IPr*OMe)­(acac)­Cl] was investigated in Buchwald–Hartwig arylamination. Catalytic activity was compared to that of [Pd­(IPr*)­(acac)­Cl].

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.

All aryl halides and amines were used as received. Anhydrous solvents (1,4-dioxane, tetrahydrofuran (THF), dimethoxyethane (DME), and toluene) and the bases (NaO t Bu, KO t Bu) were stored in a glovebox and used as received. KO t Am, received as a 1.7 M solution in toluene, was dried on a schlenk line, stored in a glovebox and used a white powder.Nickelocene was purchased from STREM chemicals and used as received.Flash chromatography was performed on silica gel 60 Å pore diameter and 40-63 µm particle size.1 H and 13 C Nuclear Magnetic Resonance (NMR) spectra were recorded on a Bruker-300 MHz or 400 MHz spectrometer at ambient temperature in CD 2 Cl 2 or CDCl 3 . Chemical shifts (δ) are reported in ppm, relative to the solvent residual peak CD 2 Cl 2 (5.32 ppm for 1 H and 54.00 ppm for 13 C) and CDCl 3 (7.26 ppm for 1 H and 77.16 ppm for 13 C). Data for 1 H NMR are reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet, br = broad signal, m = multiplet), coupling constants (J) in Hz and integration.

The synthesis of a series of digold hydroxide complexes is reported. These diaurated species, of the formula [{Au(NHC)} 2 (μ-OH)][BF 4 ] (where NHC = IPr Cl , IPr*, IPent), were easily prepared via the cationic species [Au(NHC)-(NCCH 3 )][BF 4 ] in aqueous media. The catalytic activity of these novel complexes was tested and compared to that of the previously reported IPr and SIPr derivatives. These digold hydroxide species are highly active in water-inclusive organic transformations, such as the alkyne and nitrile hydration reactions, and the Meyer−Schuster rearrangement. One salient feature of these systems is the lack of any additive to induce catalytic activity.