Monomeric copper(I) alkyl complexes that possess the N-heterocyclic carbene (NHC) ligands IPr, SIPr, and IMes [IPr ) 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, SIPr ) 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, IMes ) 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] react with amines or alcohols to release alkane and form the corresponding monomeric copper(I) amido, alkoxide, or aryloxide complexes. Thermal decomposition reactions of (NHC)Cu I methyl complexes at temperatures between 100 and 130°C produce methane, ethane, and ethylene. The reactions of (NHC)Cu(NHPh) complexes with bromoethane reveal increasing nucleophilic reactivity at the anilido ligand in the order (SIPr)Cu(NHPh) < (IPr)Cu(NHPh) < (IMes)Cu(NHPh) < (dtbpe)Cu(NHPh) [dtbpe ) 1,2-bis(di-tert-butylphosphino)ethane]. DFT calculations suggest that the HOMO for the series of Cu anilido complexes is localized primarily on the amido nitrogen with some pπ anilido −dπ Cu π*-character. [(IPr)Cu(µ-H)] 2 and (IPr)Cu(Ph) react with aniline to quantitatively produce (IPr)Cu(NHPh)/dihydrogen and (IPr)Cu(NHPh)/benzene, respectively. Analysis of the DFT calculations reveals that the conversion of [(IPr)Cu(µ-H)] 2 and aniline to (IPr)Cu(NHPh) and dihydrogen is favorable with ∆H ≈ −7 kcal/mol and ∆G ≈ −9 kcal/mol.

Catalytic carbon-carbon bond formation using transition metal complexes typically incorporates the use of an aryl halide or triflate compound (electrophile) in combination with an organometallic reagent (nucleophile). Versatile synthetic methods that allow C-C bond formation of aromatic compounds that proceed through transformation of C-H bonds would be of substantial value. Potential routes for C-C bond formation with aromatic substrates include the hydroarylation of unsaturated compounds (e.g., olefins or alkynes) and oxidative coupling of aromatic compounds and olefins or alkynes. Such reactions can proceed through metal-mediated transformation of C-H bonds. The range of reported catalysts and catalytic cycles for these classes of reactions have been reviewed herein. X = Me (70 %), OMe (73 %), Cl (74 %), Br (49 %) X OEt O X OEt O Pd(OAc) 2 (7 mol %) H 4 PMo 11 V 1 O 40 90 o C, O 2 (1 atm) + Developments in Catalytic Aromatic C-H Transformations Current

A series of monomeric (NHC)Cu(SR) (R = Ph or CH2Ph; NHC = N-heterocyclic carbene) complexes have been synthesized and fully characterized including single-crystal X-ray diffraction studies. These complexes catalyze the addition of S-H bonds across electron-deficient olefins to regioselectively produce "anti-Markovnikov" products.