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

http://journals.iucr.org/b/issues/1980/09/00/a19082/a19082.pdf

The structure of 7-chloro-1,3-dihydro-1-(N-methylacetamido)-5-phenyl-2H-1,4-benzodiazepin-2-one

Novel Layered Lithium Nitridonickelates; Effect of Li Vacancy Concentration on N Coordination Geometry and Ni Oxidation State.

The 1H n.m.r. chemical shift nonequivalence of the ortho-methyl groups in eight title compounds observed at or below ambient temperature is assigned to slow rotation about the aryl–CHMe Bond. The rotational barriers(8–17 kcal mol–1)were evaluated by lineshape analysis and compared with that in 1-mesitylethylamine. The conformation of 3,3-diphenyl-2-(1-mesitylethyl)oxaziridine (1), which shows abnormal ortho-methyl signal positions and a high rotational barrier, has been determined in the solid state by X-ray crystallography.

Dynamic stereochemistry of imines and derivatives. Part 16. Conformation and stereodynamics of oxaziridines, nitrones, and imines containing the N-(1-mesitylethyl) or (1-pentamethylphenylethyl) group; a nuclear magnetic resonance and X-ray crystallographic investigation

The crystal and molecular structure of 1Ha:2He/4Ha:5He-octafluorocyclohexane

Crystals of the title compound are monoclinic, with unit-cell dimensions a= 7.463(5), b= 13.72(l), c= 13.90(1)A, and β= 100.35(5)°, space group P21/c, and Z= 4. The structure has been determined from three- dimensional counter data and refined to R 0.045 for 1 634 observed amplitudes. The P–N bond length [1.614(2)A] indicates a considerable degree of π bonding, and the conformation about this bond is consistent with an n–σ* type of interaction. Comparison with structural data on related molecules shows that the π bonding is enhanced by electronegative substituents on the phosphorus atom. The two Pri groups are orientated differently with respect to the P–N bond. These results are discussed in relation to n.m.r. spectroscopic data which indicate that the Pri groups are non-equivalent at low temperature.

Thomas A. Hamor

Papers

The structure of 7-chloro-1,3-dihydro-1-(N-methylacetamido)-5-phenyl-2H-1,4-benzodiazepin-2-one

Novel Layered Lithium Nitridonickelates; Effect of Li Vacancy Concentration on N Coordination Geometry and Ni Oxidation State.

Dynamic stereochemistry of imines and derivatives. Part 16. Conformation and stereodynamics of oxaziridines, nitrones, and imines containing the N-(1-mesitylethyl) or (1-pentamethylphenylethyl) group; a nuclear magnetic resonance and X-ray crystallographic investigation

The crystal and molecular structure of 1Ha:2He/4Ha:5He-octafluorocyclohexane

Crystal and molecular structure of NN-di-isopropyl-p-phenylphosphon-amidic chloride, PPh(Cl)(NPri2)O