Synthesis and Characterization of Silver(I), Gold(I), and Gold(III) Complexes Bearing Amino-Functionalized N-Heterocyclic Carbenes
TL;DR: In this paper, the NHC-stabilized silver cluster (NHC)4Ag10Cl10] (5) was obtained and characterized by X-ray diffraction, showing that the carbene carbon atom exists in the rare μ2-coordination pattern, bridging two Ag(I) atoms with further stabilization of the cluster by numerous argentophilic interactions and a coordination of the amino nitrogen donor to one of the silver atoms.
About: This article is published in Organometallics.The article was published on 2011-04-26. It has received 52 citations till now. The article focuses on the topics: Carbene & Transmetalation.
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TL;DR: This review is to comprehensively describe all types of smart NHC ligands by focusing attention on the catalytically relevant ligand-based reactivity.
Abstract: It is well-recognized that N-heterocyclic carbene (NHC) ligands have provided a new dimension to the design of homogeneous catalysts. Part of the success of this type of ligands resides in the limitless access to a variety of topologies with tuned electronic properties, but also in the ability of a family of NHCs that are able to adapt their properties to the specific requirements of individual catalytic transformations. The term “smart” is used here to refer to switchable, multifunctional, adaptable, or tunable ligands and, in general, to all those ligands that are able to modify their steric or electronic properties to fulfill the requirements of a defined catalytic reaction. The purpose of this review is to comprehensively describe all types of smart NHC ligands by focusing attention on the catalytically relevant ligand-based reactivity.
684 citations
TL;DR: A series of new iridium(III) complexes containing bidentate N-heterocyclic carbenes (N HC) functionalized with an alcohol or ether group (NHC-OR, R = H, Me) catalyzed the alkylation of anilines with alcohols as latent electrophiles to obtain insights into the mechanism and into the structure of possible catalytic intermediates.
Abstract: A series of new iridium(III) complexes containing bidentate N-heterocyclic carbenes (NHC) functionalized with an alcohol or ether group (NHC?OR, R=H, Me) were prepared. The complexes catalyzed the ...
150 citations
TL;DR: Direct dehydrogenative silylation of pyridyl and iminyl substrates with triethylsilane was achieved using (L)Ir(cod)(X) (1) (L = a perimidine-based carbene ligand) complexes as catalysts under toluene refluxing conditions in the presence of norbornene as a hydrogen scavenger, and the silylated products were obtained in good yields.
Abstract: Direct dehydrogenative silylation of pyridyl and iminyl substrates with triethylsilane was achieved using (L)Ir(cod)(X) (1) (L = a perimidine-based carbene ligand, X = OAc and OCOPh) complexes as catalysts under toluene refluxing conditions in the presence of norbornene as a hydrogen scavenger, and the silylated products were obtained in good yields. The isolated bis(cyclometalated)iridium complexes, (C∧C:)(C∧N)IrOAc (2) (C∧C: = a cyclometalated perimidine-carbene ligand and C∧N = a cyclometalated pyridyl- and iminyl-ligated aromatic substrate), were key intermediates, where cyclometalated five-membered metallacycles of substrates such as phenylpyridine were selectively formed before yielding mono-ortho-silylation products. The bis(cyclometalated)iridium complex (XyC∧C:)(C∧N)IrOAc (2d) (XyC∧C: = a cyclometalated N-xylyl-N′-methylperimidine-carbene ligand and C∧N = a 2-pyridylphenyl ligand), reacted with 2 equiv of Et3SiH to give an iridium hydride complex, (L4)(C∧N)Ir(H)(SiEt3) (8d) (L4 = N-CH3, N-3,5-(CH...
96 citations
TL;DR: In this paper, two N-heterocyclic carbene (NHC) ligands and two chloride ligands were used to synthesize an Au(III)-NHC complex supported by two NHC ligands.
63 citations
TL;DR: Guanidine-NHC Ag and Cu complexes are found to be versatile catalysts for hydroboration, semihydrogenation and carboboration of alkynes in a highly stereo- and regioselective fashion.
58 citations
References
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TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
Abstract: Despite the remarkable thermochemical accuracy of Kohn–Sham density‐functional theories with gradient corrections for exchange‐correlation [see, for example, A. D. Becke, J. Chem. Phys. 96, 2155 (1992)], we believe that further improvements are unlikely unless exact‐exchange information is considered. Arguments to support this view are presented, and a semiempirical exchange‐correlation functional containing local‐spin‐density, gradient, and exact‐exchange terms is tested on 56 atomization energies, 42 ionization potentials, 8 proton affinities, and 10 total atomic energies of first‐ and second‐row systems. This functional performs significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
87,732 citations
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
Abstract: A correlation-energy formula due to Colle and Salvetti [Theor. Chim. Acta 37, 329 (1975)], in which the correlation energy density is expressed in terms of the electron density and a Laplacian of the second-order Hartree-Fock density matrix, is restated as a formula involving the density and local kinetic-energy density. On insertion of gradient expansions for the local kinetic-energy density, density-functional formulas for the correlation energy and correlation potential are then obtained. Through numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, it is demonstrated that these formulas, like the original Colle-Salvetti formulas, give correlation energies within a few percent.
84,646 citations
TL;DR: This work reports a gradient-corrected exchange-energy functional, containing only one parameter, that fits the exact Hartree-Fock exchange energies of a wide variety of atomic systems with remarkable accuracy, surpassing the performance of previous functionals containing two parameters or more.
Abstract: Current gradient-corrected density-functional approximations for the exchange energies of atomic and molecular systems fail to reproduce the correct 1/r asymptotic behavior of the exchange-energy density. Here we report a gradient-corrected exchange-energy functional with the proper asymptotic limit. Our functional, containing only one parameter, fits the exact Hartree-Fock exchange energies of a wide variety of atomic systems with remarkable accuracy, surpassing the performance of previous functionals containing two parameters or more.
45,683 citations
TL;DR: The methods presented in the chapter have been applied to solve a large variety of problems, from inorganic molecules with 5 A unit cell to rotavirus of 700 A diameters crystallized in 700 × 1000 × 1400 A cell.
Abstract: Publisher Summary X-ray data can be collected with zero-, one-, and two-dimensional detectors, zero-dimensional (single counter) being the simplest and two-dimensional the most efficient in terms of measuring diffracted X-rays in all directions. To analyze the single-crystal diffraction data collected with these detectors, several computer programs have been developed. Two-dimensional detectors and related software are now predominantly used to measure and integrate diffraction from single crystals of biological macromolecules. Macromolecular crystallography is an iterative process. To monitor the progress, the HKL package provides two tools: (1) statistics, both weighted (χ2) and unweighted (R-merge), where the Bayesian reasoning and multicomponent error model helps obtain proper error estimates and (2) visualization of the process, which helps an operator to confirm that the process of data reduction, including the resulting statistics, is correct and allows the evaluation of the problems for which there are no good statistical criteria. Visualization also provides confidence that the point of diminishing returns in data collection and reduction has been reached. At that point, the effort should be directed to solving the structure. The methods presented in the chapter have been applied to solve a large variety of problems, from inorganic molecules with 5 A unit cell to rotavirus of 700 A diameters crystallized in 700 × 1000 × 1400 A cell.
31,667 citations
TL;DR: In this article, effective core potentials (ECP) have been derived to replace the innermost core electron for third row (K), fourth row (Rb-Ag), and fifth row (Cs-Au) atoms.
Abstract: Ab initio effective core potentials (ECP’s) have been generated to replace the innermost core electron for third‐row (K–Au), fourth‐row (Rb–Ag), and fifth‐row (Cs–Au) atoms The outermost core orbitals—corresponding to the ns2np6 configuration for the three rows here—are not replaced by the ECP but are treated on an equal footing with the nd, (n+1)s and (n+1)p valence orbitals These ECP’s have been derived for use in molecular calculations where these outer core orbitals need to be treated explicitly rather than to be replaced by an ECP The ECP’s for the forth and fifth rows also incorporate the mass–velocity and Darwin relativistic effects into the potentials Analytic fits to the potentials are presented for use in multicenter integral evaluation Gaussian orbital valence basis sets are developed for the (3s, 3p, 3d, 4s, 4p), (4s, 4p, 4d, 5s, 5p), and (5s, 5p, 5d, 6s, 6p) ortibals of the three respective rows
13,717 citations