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

Ring Opening and Oligomerization of Thiirane by Hexaosmium Carbonyl Cluster Complexes.

New Manganese Pyrophosphates: Syntheses, Crystallographic Characterizations and Magnetic Properties of BaMnP2O7 and CaMnP2O7.

Cluster Synthesis. Part 28. New Platinum‐Cobalt Carbonyl Cluster Complexes and Products Obtained from Their Reactions with Alkynes.

The new compound BaCo 2 Si 2 O 7 was obtained by heating the mixture BaCO 3 , CoCO 3 and SiO 2 to 1300°C for 48 h. The material was characterized by single-crystal X-ray diffraction and magnetic susceptibility measurements. Each cobalt ion is surrounded by four oxygen atoms arranged in a distorted tetrahedral shape. These tetrahedral are linked into chains through the sharing of one of the oxygen atoms. The CoO 4 chains are cross-linked by bridging Si 2 O 7 groups. The barium ions occupy channels that run parallel to the crystallographic c -axis. The effective magnetic moment, μ eff = 4.70 B.M., at 25°C is consistent with Co 2+ in a tetrahedral environment having three unpaired electrons. Anti-ferromagnetic coupling of the electrons occurs between the nearest neighbour cobalt ions, as indicated by the sign of the Weiss constant, θ p = −46 K, and by the presence of a broad maximum in the susceptibility curve. At 26 K it undergoes a three-dimensional magnetic transition into a field-induced weak ferromagnet that is characteristic of a one-dimensional metamagnet.

BaCo2Si2O7: A New One-Dimensional Antiferromagnet Based on Chains of Oxide Bridged CoO4 Tetrahedra.

The reaction of the new carbene-containing cluster complex Os{sub 3}(CO){sub 11}(C(Et)NMe{sub 2}) (2) with PhC{triple bond}CH has yielded the complex Os{sub 3}(CO){sub 9}({mu}{sub 3}-PhC{sub 2}{l brace}C(Et)(NMe{sub 2}){r brace})({mu}-H) (3, 35%), which contains a triply bridging alkyne ligand with phenyl and ethyl(dimethyliminio)methyl substituents. The product is believed to have been formed by the transfer of the C(Et)NMe{sub 2} carbene ligand in 2 to the {alpha}-carbon atom of a bridging PhC{triple bond}C ligand in an intermediate formed by the activation of PhC{triple bond}CH by the cluster.

Richard D. Adams

Papers

Ring Opening and Oligomerization of Thiirane by Hexaosmium Carbonyl Cluster Complexes.

New Manganese Pyrophosphates: Syntheses, Crystallographic Characterizations and Magnetic Properties of BaMnP2O7 and CaMnP2O7.

Cluster Synthesis. Part 28. New Platinum‐Cobalt Carbonyl Cluster Complexes and Products Obtained from Their Reactions with Alkynes.

BaCo2Si2O7: A New One-Dimensional Antiferromagnet Based on Chains of Oxide Bridged CoO4 Tetrahedra.

Clusters Containing Carbene Ligands. Novel Example of Carbene Ligand Transfer from a Metal Atom to a Carbon Atom.