Hydroxide complexes coordination chemistry

Lanthanide Complexes with Multidentate Ligands Lanthanide Oxide/Hydroxide Complexes Lanthanides Coordination Chemistry Solvento Complexes of the Lanthanide Ions Trivalent Chemistry Cyclopentadienyl. 

The fact that tantalum and niobium complexes form in fluoride solutions not only supplements fundamental data on the coordination chemistry of fluoride compounds, but also has a broad practical importance. This type of solution is widely used in the technology of tantalum and niobium compounds in raw material digestion, liquid-liquid extraction, precipitation and re-pulping of hydroxides, and in the crystallization and re-crystallization of K-salts and other complex fluoride compounds. 

Malonic acid CH2(C02H)2 (H2mal) (209) has a coordination chemistry with chrommm(III) closely resembling that of oxalate. Malonic acid is a slightly weaker acid than oxalic acid and slightly more labile complexes are formed. The tris complex is the most extensively studied, prepared by the reduction of chromate solutions or the reaction of chromium(III) hydroxide with malonate.917,918 919 The cis and trans diaqua complexes may be prepared by the reduction of chromate with malonate the isomers are separated by fractional crystallization. The electronic spectrum of the tris complex is similar to that of the tris oxalate and a detailed analysis of these spectra has appeared.889... 

The coordination chemistry of sea water represents a new and useful approach to understanding the chemical properties of sea water. The coordination chemistry of sea water differs from contemporary coordination chemistry in the following respects most complexes involve pretransition metals, most complexes are labile, the ligands are simpler (water, hydroxide, chloride, carbonate, sulfate), and time and space are important parameters. Principles of coordination chemistry are applied to contemporary research in marine science in four areas analysis of constituents of natural waters, the nature of metallic species in the oceans, the Red Tide problem, and carbonate geochemistry. 

A final example concerns the formation of heteropolynuclear hydroxide complexes.116 The complexes [(OH)Fe(OH)2Cr]3+, [(OH)Fe(OH)2Cr(OH)]2+ and [(OH)2Fe(OH)2Cr(OH)]+, or polymers such as Fe(OH)2M "+ (M = V, Cr, Mn, Co, Ni, Cu n = 2-4) have been studied with a view to an understanding of the inclusion of transition metals in iron ores as mixed oxides rather than their occurrence as discrete mineral phases. Many other examples might have been chosen in this section. Reference should be made to the general reviews given above. However it should be clear that simple inorganic coordination complexes play a major role in the chemistry of natural aqueous systems at low temperatures. 

Aluminum occurs widely in nature in silicates such as micas and feldspars, complexed with sodium and fluorine as cryolite, and in bauxite rock, which is composed of hydrous aluminum oxides, aluminum hydroxides, and impurities such as free silica (Cotton and Wilkinson 1988). Because of its reactivity, aluminum is not found as a free metal in nature (Bodek et al. 1988). Aluminum exhibits only one oxidation state (+3) in its compounds and its behavior in the environment is strongly influenced by its coordination chemistry. Aluminum partitions between solid and liquid phases by reacting and complexing with water molecules and anions such as chloride, fluoride, sulfate, nitrate, phosphate, and negatively charged functional groups on humic materials and clay. 

Basolo, F. Theories of Acids, Bases, Amphoteric Hydroxides, and Basic Salts as Applied to the Chemistry of Complex Compounds, in Bailar and Busch s Chemistry of Coordination Compounds, 416-447, Reinhold Publishing Co., New York (1956). 

The large number of lanthanide alkoxide complexes featuring the inclusion of oxo or hydroxo groups unmistakably suggests that the coordination chemistry of lanthanide hydroxide is intimately associated with that of the alkoxides. Arguably the simplest and most ubiquitous O-containing ligand, the water molecule, occupies a special position in the development of lanthanide coordination chemistry. Upon coordination to the Lewis acidic lanthanide ion, an... 

Transition metal complexes can promote reactions by organizing and binding substrates. We have already seen this in terms of metal-directed reactions. Another important function is the supply of a coordinated nucleophile for the reaction, which is incorporated in the product. We have already seen a coordinated nucleophile at work in the reaction discussed above of Co— OH with NO+ nucleophiles, which are electron-rich entities, are best represented in coordination chemistry by coordinated hydroxide ion, formed by proton loss from a water molecule this is a common ligand in metal complexes. Normally, water dissociates only to a very limited extent, via... 

All phases of coordination chemistry are encompassed by the complex chromium(III) azides. A yellow, crystalline salt of the composition [Cr (NH3)6] (N3)3, for example, is not a true azido complex but the azide salt of the hexammmechromium(III) cation. It is soluble in water the heated solution aquates over a red intermediate, aquopentamminechromium, to chromium hydroxide. The dry salt explodes in the match test. Similarly explosive is the neutral complex triamminetriazidochromium(III), [(NH3)3Cr (N3)3]°, an olive-green, crystalline solid which is, expectedly, insoluble in water and organic solvents it explodes thermally within 25 sec at 250°, and within 1 sec at 300°C, and also on impact [145]. The compound was made by heating a solution of 10 g hexamminechromium perchlorate, 10 g ammonium sulfate, and 50 g sodium azide in 300 ml water for 90 min. 

Adsorption on Oxide/Hydroxide Suifrices Since the metal species at oxide or hydroxide surfaces are present in form of isolated cations (i.e. nonzerovalent species), separated from each other by 0 or OH anions, they resemble the metal centers of mononuclear metal complexes in solution more than metal atoms in a bare metal surface. Consequently, concepts from coordination chemistry of the corresponding solute complexes can be applied more readily in this case. The exposed cations and anions on oxide surfaces can be regarded as hard acids and bases, respectively. Studies of oxide single crystals under ultrahigh vacuum (UHV) conditions identified three key concepts to describe the surface chemistry of metal oxides [27] ... 

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