The monomeric Cu(I) complexes (IPr)Cu(Z) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, Z = NHPh, OEt, or OPh) react with YH (Y = PhNH, PhCH2NH, EtO, or PhO) to catalytically add Y-H bonds across the C=C bond of electron-deficient olefins to yield anti-Markovnikov organic products. Catalytic activity has been observed for olefins CH2C(H)(X) with X = CN, C(O)Me, or CO2Me as well as crotononitrile. Preliminary studies implicate an intermediate in which the C-Y bond forms through a nucleophilic addition pathway.

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.

Synthesis and isolation of the Cu(I) amido complex (dtbpe)Cu(NHPh) (dtbpe = 1,2-bis(di-tert-butylphosphino)ethane) is accomplished upon reaction of [(dtbpe)Cu(mu-Cl)](2) with LiNHPh. The anilido complex has been fully characterized by IR spectroscopy and multinuclear NMR spectroscopy as well as by single-crystal X-ray diffraction study. Salient features of the solid-state structure include an amido orientation that allows pi-interaction of the nitrogen-based lone pair with both the empty copper p-orbital and the pi-system of the phenyl substituent. A solid-state X-ray diffraction study of [(dtbpe)Cu(NH(2)Ph)][BF(4)] has allowed a direct comparison of the structural features upon conversion of the amine ligand to an amido. The reactivity of the amido ligand of (dtbpe)Cu(NHPh) is consistent with nucleophilic character. For example, the formation of Ph(3)CNHPh is observed upon treatment with [Ph(3)C][BF(4)], and reaction at room temperature with EtX (X = Br or I) yields N-ethylaniline. The reactivity of (dtbpe)Cu(NHPh) is compared to that of the octahedral and d(6) complex TpRu(PMe(3))(2)(NHPh) (Tp = hydridotris(pyrazolyl)borate).

Monomeric copper(I) amido, alkoxide, and aryloxide complexes catalyze the addition of N−H and O−H bonds of amines and alcohols, respectively, to electron-deficient olefins. The ancillary ligands of the active catalysts include the N-heterocyclic carbene (NHC) ligands IPr, IMes, and SIPr {IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene; SIPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene} as well as the chelating bisphosphine ligand dtbpe {dtbpe = 1,2-bis(di-tert-butylphosphino)ethane}. For the hydroamination and hydroalkoxylation of olefins, both aromatic and alkyl substituents can be incorporated into the nucleophile, and both primary and secondary amines are reactive. Monosubstituted and disubstituted olefins have been demonstrated to undergo reaction. For the addition of aniline to acrylonitrile, kinetic studies suggest a pathway that is dependent on the concentration of amine, olefin, and catalyst as well as inversely proportional to the concentration of the product 3-anilinopropionitrile. At low concentrations, the addition of tert-butylisonitrile increases the rate of catalysis. The proposed mechanism involves N−C or O−C bond formation by an intermolecular nucleophilic addition of the amido, alkoxide, or aryloxide ligand to free olefin.

Monomeric Cu(I) amido and thiolate complexes that are supported by the N-heterocyclic carbene ligand 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) catalyze the hydroamination and hydrothiolation of electron-deficient vinylarenes with reactivity patterns that are consistent with an intermolecular nucleophilic addition of the amido/thiolate ligand of (IPr)Cu(XR) (X = NH or S; R = Ph, CH2Ph) to free vinylarene.

Monomeric Cu(I) alkyl complexes (NHC)Cu(R) (NHC ) N-heterocyclic carbene; R ) Me or Et) and (dtbpe)Cu(Me) (dtbpe ) 1,2-bis(di-tert-butylphosphino)ethane) have been prepared, isolated, and characterized. Single-electron oxidation of the Cu(I) alkyl complexes upon reaction with AgOTf to form putative Cu(II) intermediates of the type [(L)Cu(R)] + (L ) NHC or dtbpe, R ) Me or Et) results in the rapid production of (L)Cu(X) (X ) OTf) and R 2 . Experimental studies suggest that the reductive elimination of R 2 from Cu(II) occurs through a nonradical bimolecular mechanism. Computational studies of the Cu-C methyl yield bond dissociation enthalpies of [(SIPr)Cu-CH 3 ] n+ (80 kcal/mol for n ) 0 {Cu(I)} and 38 kcal/mol for n ) 1 {Cu(II)}).

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