1. Advantages of Chemical Redox Agents 878 2. Disadvantages of Chemical Redox Agents 879 C. Potentials in Nonaqueous Solvents 879 D. Reversible vs Irreversible ET Reagents 879 E. Categorization of Reagent Strength 881 II. Oxidants 881 A. Inorganic 881 1. Metal and Metal Complex Oxidants 881 2. Main Group Oxidants 887 B. Organic 891 1. Radical Cations 891 2. Carbocations 893 3. Cyanocarbons and Related Electron-Rich Compounds 894

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Chemical Redox Agents for Organometallic Chemistry

Interest in catalysis by metal nanoparticles (NPs) is increasing dramatically, as reflected by the large number of publications in the last five years. This field, "semi-heterogeneous catalysis", is at the frontier between homogeneous and heterogeneous catalysis, and progress has been made in the efficiency and selectivity of reactions and recovery and recyclability of the catalytic materials. Usually NP catalysts are prepared from a metal salt, a reducing agent, and a stabilizer and are supported on an oxide, charcoal, or a zeolite. Besides the polymers and oxides that used to be employed as standard, innovative stabilizers, media, and supports have appeared, such as dendrimers, specific ligands, ionic liquids, surfactants, membranes, carbon nanotubes, and a variety of oxides. Ligand-free procedures have provided remarkable results with extremely low metal loading. The Review presents the recent developments and the use of NP catalysis in organic synthesis, for example, in hydrogenation and C--C coupling reactions, and the heterogeneous oxidation of CO on gold NPs.

Nanoparticles as Recyclable Catalysts: The Frontier between Homogeneous and Heterogeneous Catalysis

Metal species with different size (single atoms, nanoclusters, and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that many factors including the particle size, shape, chemical composition, metal–support interaction, and metal–reactant/solvent interaction can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow one to correlate the relationships at the molecular level. In this Review, the electronic and geometric structures of single atoms, nanoclusters, and nanoparticles will be discussed. Furthermore, we will summarize the catalytic applications of single atoms, nanoclusters, and nanoparticles for different types of reactions, including CO oxidation, selective oxidation, selective hydrogenation, organic reactions, electrocatalytic, and photocatalytic reactions. We will compare the results o...

Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles.

Efficient and reliable amplification of chirality has borne its greatest fruit with transition metal-catalyzed reactions since enantiocontrol may often be imposed by replacing an achiral or chiral racemic ligand with one that is chiral and scalemic While the most thoroughly developed enantioselective transition metal-catalyzed reactions are those involving transfer of oxygen (epoxidation and dihydroxylation)1,2 and molecular hydrogen,3 the focus of this review is on the area of enantioselective transition metal-catalyzed allylic alkylations which may involve C-C as well as C-X (X ) H or heteroatom) bond formation4-9 The synthetic utility of transitionmetal-catalyzed allylic alkylations has been soundly demonstrated since its introduction nearly three decades ago10-21 In contrast to processes where the allyl moiety acts as the nucleophilic partner, we will limit our discussion to processes which result in nucleophilic displacements on allylic substrates (eq 1) Such reactions have been recorded with a broad

http://web4.uwindsor.ca/users/j/jlichaa/reference.nsf/0/10ff8b04ff3a317885256d88005720f6/$FILE/cr-1996-96-395-allylpd-asym.pdf

Asymmetric Transition Metal-Catalyzed Allylic Alkylations.

This critical review presents a comprehensive study of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) towards construction and synthesis of metal–organic frameworks (MOFs). We describe the geometries of 131 SBUs, their connectivity and composition. This contribution presents a comprehensive list of the wide variety of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) in the construction and synthesis of metal–organic frameworks. The SBUs discussed here were obtained from a search of molecules and extended structures archived in the Cambridge Structure Database (CSD, version 5.28, January 2007) which included only crystals containing metal carboxylate linkages (241 references).

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Secondary building units, nets and bonding in the chemistry of metal–organic frameworks

Transformation of alkenyl-N-arylthioamido ligands into quinoline-2-thiolate ligands in dirhenium carbonyl complexes

Energy capture by a tetranuclear metal cluster complex. Synthesis and characterization of PtOs3(CO)10(.mu.-.eta.2-dppm)[Si(OMe)3](.mu.-H) and its metastable photoisomer

Positively charged ligands. The coordination behavior of sulfonium cations

The electronically unsaturated compounds Re2(CO)8[μ-Au(NHC)](μ-Ph), 1, and Re2(CO)8[μ-Au(NHC)]2, 2, were obtained from the reaction of Re2(CO)8[μ–η2-C(H)═C(H)Bun](μ-H) with MeAu(NHC), NHC = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene. Compound 1 was converted to the new compound Re2(CO)8[μ-Au(NHC)](μ-H), 3, by reaction with H2. Addition of CO to 3 yielded the new compound Re2(CO)9[Au(NHC)](μ-H), 4, which contains a terminally coordinated Au(NHC) group on one of the rhenium atoms, and the hydrido ligand was shifted to bridge the Re–Au bond. The mechanism of the formation of 4 was established by DFT computational analyses. Compound 3 also reacted with C2H2 by an addition with insertion into the Re–H bonds to yield the compound Re2(CO)8[μ-Au(NHC)](μ-C2H3), 5, which contains a σ–π coordinated, bridging C2H3 ligand. The stereochemistry of the insertion was found to proceed preferentially with a cis- (syn-) stereochemistry. Compound 1 reacted with HCl to yield Re2(CO)8[μ-Ph](μ-H), 6, and ClAu(NHC) by selec...

Synthesis and Reactivity of Electronically Unsaturated Dirhenium Carbonyl Compounds Containing Bridging Gold-Carbene Groups

The new mixed metal carbide containing cluster compounds PtFe4(CO)12(COD)(μ5-C) 1 and PtFe4(CO)12(PMe2Ph)2(μ5-C), 2 were obtained by metal–metal exchange reactions between [Et4N]2[Fe5(C)(CO)14] with Pt(COD)Cl2 in the presence of TIPF6 and Pt(PMe2Ph)2Cl2, respectively. Compound 1 was also obtained by the reaction of Fe5(CO)15(μ5-C) with Pt(COD)2 in the presence of UV irradiation but in a lower yield. Both compounds were characterized by a combination of IR, 1H NMR and single crystal x-ray diffraction analyses. Both complexes consists of a square pyramidal cluster of five metal atoms with an “interstitial” carbido ligand in the center of the square base. The phosphine ligands in 2 undergo a dynamical intramolecular interchange at a rate that is fast on the 1H NMR time scale at 45°C, ΔG† (at 318 K)=15.1 kcal/mol.

New Mixed Metal Cluster Complexes Containing Platinum. The Synthesis and Structural Characterizations of PtFe~4(CO)~1~2(COD)(mu~5-C) and PtFe~4(CO)~1~2(PMe~2Ph)~2(mu~5-C)

Richard D. Adams

Papers

Transformation of alkenyl-N-arylthioamido ligands into quinoline-2-thiolate ligands in dirhenium carbonyl complexes

Energy capture by a tetranuclear metal cluster complex. Synthesis and characterization of PtOs3(CO)10(.mu.-.eta.2-dppm)[Si(OMe)3](.mu.-H) and its metastable photoisomer

Positively charged ligands. The coordination behavior of sulfonium cations

Synthesis and Reactivity of Electronically Unsaturated Dirhenium Carbonyl Compounds Containing Bridging Gold-Carbene Groups

New Mixed Metal Cluster Complexes Containing Platinum. The Synthesis and Structural Characterizations of PtFe~4(CO)~1~2(COD)(mu~5-C) and PtFe~4(CO)~1~2(PMe~2Ph)~2(mu~5-C)