Carboxylates polynuclear compounds

The hydrogen atom in the ortho position to the carbonyl group unites with the hydroxyl group of the carboxyl to effect the ring closure. The preparation of o-benzoylbenzoic acid from benzene and phthalic anhydride (Experiment 63) and the dehydration of this keto acid to anthraquinone considered in the present experiment illustrate the building up of polynuclear compounds from simpler benzene derivatives. 

There are many bi- and polynuclear iron(III) complexes where bridging oxide is supported by carboxylates. Combinations of Fe—O—Fe plus carboxylate bridges occur in model compounds for proteins and in biomineralization. Electronic spectra of [Fe(/u-0)(//-02CR)2Fe] complexes have been reviewed briefly. [Fe2(//-0)(M-02CMe)2(bipy)2Cl2] is both an alkane activation catalyst and a bio-model. ... 

For practical purposes the field of metal-metal bonds and metal atom clusters can be divided into two broad areas. (1) Those compounds with the metal atoms in formal oxidation states of zero or close to it, including negative ones. For the most part these are polynuclear metal carbonyls, or very similar compounds. In these compounds the M-M bonds are usually long, weak and of order one. (2) Compounds with the metal atoms in low to medium positive oxidation states, and ligands of the same kinds normally found in classical Werner complexes, e.g., halide, sulfate, phosphate, carboxylate or thiocyanate ions, water, amines and phosphines. Compounds of this type include metal-metal bonds of orders ranging from about 1/2 to 4.0. 

Copper(I) Carboxylates, Triflate, Alkoxides, and Dialky lamides. Thecarbox-ylates have varied structures. The acetate that is obtained as white air-sensitive crystals by reduction of Cu11 acetate by Cu in pyridine or MeCN has a planar chain structure (17-H-I). By contrast the trifluoroacetate [Cu02CCF3]4-2C,H6, and benzoate [Cu02CPh]4 complexes are tetramers with bridging carboxylates as in (17-H-II). This is only one type of Cut polynuclear structure (see later). There are also bridged pyrazole and pyrazolylborate compounds. 

Similarly, the nitride, carbide, cyanide, carboxylate, and carbonate salts of aluminum are unstable in aqueous solution. Aluminum salts of strong acids form solutions of the hydrated cation (see Hydrates). These solutions are acidic owing to the partial dissociation of one of the coordinated water molecules (equation 6), the p/fa of [A1(H20)6] + being 4.95 (see Acidity Constants). Note that this is quite similar to that of acetic acid. The second step in the hydrolysis reaction yields a dihydroxide species that undergoes condensation to form polynuclear cations (see Section 8). Antiperspirants often include an ingredient called aluminum chlorhydrate that is really a mixture of the chloride salts of the monohydroxide and dihydroxide aluminum cations. The aluminum in these compounds causes pores on the surface of the skin to contract leading to a reduction in perspiration. 

The oxidative cleavage of carbon-carbon bonds in vicinal diols [756, 759] is a reaction widely used in saccharide chemistry. Besides its application in this reaction, periodic acid achieves the oxidative coupling [757] or oxidation to quinones [758] of polynuclear aromatic hydrocarbons, the oxidation of methyl groups in aromatic compounds to carbonyl groups [760], the conversion of epoxides into dicarbonyl compounds [761], and the oxidative cleavage of trimethylsilyl ethers of acyloins to carboxylic acids [755]. 

Organotin carboxylates and sulfonates form an important class among the family of organotin compounds.These compounds possess rich structural diversity. A range of structures from simple mononuclear compounds to complex polynuclear cages and clusters are formed." The structural diversity of these compounds emanates from several features. These include ... 

The reactions involved in the chrome-tanning process are those of coordination complexes. They involve the interaction between charged carboxyl groups on the collagen macromolecule and polynuclear chromium(III) coordination compounds. The most widely used chrome-tanning material is 33% basic chromium(III) sulfate produced industrially by reducing sodium dichromate with sulfur dioxide. 

Subsequent research showed the SrnI mechanism to occur with many other aromatic compounds. The reaction was found to be initiated by solvated electrons, by electrochemical reduction, and by photoinitiated electron transferNot only I, but also Br, Cl, F, SCeHs, N(CH3)3, and 0P0(0CH2CH3)2 have been foimd to serve as electrofuges. In addition to amide ion, phosphanions, thiolate ions, benzeneselenolate ion (C HsSe"), ketone and ester enolate ions, as well as the conjugate bases of some other carbon acids, have been identified as nucleophiles. The SrnI reaction was observed with naphthalene, phenanthrene, and other polynuclear aromatic systems, and the presence of alkyl, alkoxy, phenyl, carboxylate, and benzoyl groups on the aromatic ring does not interfere with the reaction. ... 

PE Unsaturations, aromatic carbonyl compounds, hydrogen at tertiary carbon, aromatic amines, groups formed during oxidation (hydroperoxides, carbonyl, carboxyl, hydroxyl), benzophenones, quinones, transition metal compounds, TiOs, polynuclear aromatics Free radiceds, crosslinks Free radicals, hydroperoxides, carbonyl groups, chain scissions... 

Between 1961 and 1967 the electrochemical generation method has been used to obtain, identify, and investigate free radicals derived from about 400 different organic compounds, such as unsaturated acyclic and alicyclic hydrocarbons, condensed and noncondensed polynuclear aromatic hydrocarbons, heterocyclic compounds, quinones, carbonyl compounds, nitriles, nitroso and nitro derivatives, and carboxylic esters. 

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