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

Synthetic organic chemists enjoy the luxury of having a large collection of reliable reactions at their disposal for preparing small molecules, mesoscopic structures, and polymers. Coordination chemists, on the other hand, are faced with the fact that transition metal chemistry, when normalized for the number of transition metals, has relatively few high-yielding reactions, when compared to the chemistry of carbon, for preparing even small molecule structures. This lack of control is manifested, in large part, in the weak metal-ligand interactions found in coordination complexes as compared with the strong covalent bonds in organic compounds. Weak bonding often translates into many reaction pathways that are not substantially different from an energetic point of view, and therefore, results in poor selectivity. As a result, many coordination chemists in recent years have come to the realization that it may be easier and more productive to develop straightforward and reliable routes to mesoscopic supramolecular structures by capitalizing on the modest collection of high-yielding reactions in coordination chemistry, the directional bonding afforded by metal centers, and strategies aimed at taking advantage of the weak metal bonds found in coordination complexes. Three emerging synthetic strategies, the symmetry-interaction, directional-bonding, and weak-link synthetic approaches, all use metal centers as structural building blocks to rationally assemble molecular components into supramolecular metallocyclophanes. These three approaches are discussed herein, and the fundamental principles underlying each as well as their capabilities are compared and contrasted.

Strategies for the Construction of Supramolecular Compounds through Coordination Chemistry

Crown ethers: sensors for ions and molecular scaffolds for materials and biological models.

Iron-catalyzed hydroxyl radical formation. Stringent requirement for free iron coordination site.

The literature has shown numerous contributions on the synthesis and physicochemical properties of persistent organic radicals but there are a lesser number of reports about their use as building blocks for obtaining molecular magnetic materials exhibiting an additional and useful physical property or function. These materials show promise for applications in spintronics as well as bistable memory devices and sensing materials. This critical review provides an up-to-date survey to this new generation of multifunctional magnetic materials. For this, a detailed revision of the most common families of persistent organic radicals—nitroxide, triphenylmethyl, verdazyl, phenalenyl, and dithiadiazolyl—so far reported will be presented, classified into three different sections: materials with magnetic, conducting and optical properties. An additional section reporting switchable materials based on these radicals is presented (257 references).

Playing with organic radicals as building blocks for functional molecular materials

Stereochemistry of Ethylenediaminetetraacetato Complexes. II. The Structure of Crystalline Rb[Fe(OH2)Y].H2O. III. The Structure of Crystalline Li[Fe(OH2)Y.2H2O

The Structure of Crystalline Tetraphenylporphine. The Stereochemical Nature of the Porphine Skeleton

The Crystal Structure and Molecular Stereochemistry of Methoxyiron (III) Mesoporphyrin-IX Dimethyl Ester1

The syntheses and spectroscopic data (13C n.m.r.) for some new organyltellurium ligands are described. Thus trans metallation of 2-(2-pyridyl)phenyl-(R) or 2-(quinolin-2-yl)phenyl-(R′) mercury(II) chloride with TeBr4 gives the organyltellurium tribromides RTeBr3 and R′TeBr3, which may be reduced to the organyltellurium bromides RTeBr and R′TeBr, some metathesis reactions of which are described; or, in the presence of excess hydrazine, to diorganyl ditellurides, R2Te2 and R′2Te2. Reduction of RTeBr3X with NaBH4 gave a novel tritelluride, R2Te3; a method of preparation for R′2Te3 was also devised. Syntheses of the tellurides R2Te, R′2Te, and RTe(C6H4OEt-p) were developed and the intermediacy of ionic compounds [R2TeBr][HgClBr2] and [R2TeCl][HgCl3] noted. The crystal structures of 2-(2-pyridyl)phenyltellurium(IV) tribromide, (1), dimethyldithiocarbamato [2-(2-pyridyl)phenyl]tellurium(II), (2), and p-ethoxyphenyl 2-(2-pyridyl)phenyltelluride, (3), have been determined from three-dimensional X-ray counter data. Complex (1) is triclinic, space group P with a= 6.953(6), b= 8.382(1), c= 12.133(2)A, α= 78.68(1), β= 82.87(4), γ= 87.14(4)°, and Z= 2; R= 0.0735 for 1 963 observed reflections. The co-ordination about Te is octahedral with a vacant equatorial position, two Br atoms apical, the third Br and the organic group equatorial [Te–C, 2.110(19); Te–N, 2.244(14)A]. The compound is essentially monomeric, with a weak association between Te and Br [3.596(3)A] in a neighbouring molecule. Complex (2) is triclinic, space group P with a= 8.809(3), b= 9.032(5), c= 10.727(4)A, α= 83.06(4), β= 86.49(3), γ= 63.68(4), and Z= 2; R= 0.0417 for 2 502 observed reflections. The co-ordination about Te is trigonal bipyramidal, C(1) and two lone pairs of Te comprising the equatorial co-ordination and the S(1) atom together with the pyridyl-N atom axial [Te–C, 2.111(5); Te–N, 2.354(4)A]. No significant intermolecular contacts occur. Complex (3) is monoclinic, space group P21/c with a= 13.422(2), b= 16.469(3), c= 7.711(3)A, β= 91.01(2)°, and Z= 4; R= 0.0415 for 2 014 observed reflections. The Te atom is bonded to two C atoms. The N atom of the pyridyl ring is twisted away from Te [Te–N, 2.695(4)A] by rotation of the pyridyl ring about the pyridyl–phenyl bond by 23.2(3)°, a manifestation of the trans effect of the Te–C(ethoxyphenyl) covalent bond.

2-Pyridyl- and quinolin-2-yl-functionalised organyltellurium ligands. The stabilisation of diorganyl tritellurides. The crystal and molecular structures of 2-(2-pyridyl)phenyltellurium(IV) tribromide, dimethyldithiocarbamato[2-(2-pyridyl)phenyl]tellurium(II), and p-ethoxyphenyl 2-(2-pyridyl)phenyl telluride

Thomas A. Hamor

Papers

Stereochemistry of Ethylenediaminetetraacetato Complexes. II. The Structure of Crystalline Rb[Fe(OH2)Y].H2O. III. The Structure of Crystalline Li[Fe(OH2)Y.2H2O

The Structure of Crystalline Tetraphenylporphine. The Stereochemical Nature of the Porphine Skeleton

The Crystal Structure and Molecular Stereochemistry of Methoxyiron (III) Mesoporphyrin-IX Dimethyl Ester1

The Crystal and Molecular Structure of Nickel (II) 2,4-Diacetyldeuteroporphyrin-IX Dimethyl Ester1