Hydroxide complexes properties

Shock EL, Sassani DC, Willis M, Sverjensky DA (1997) Inorganic species in geologic fluids Correlations among standard molal thermodynamic properties of aqueous cations and hydroxide complexes. Geochim... 

The physical properties of many macrocyclic polyethers and their salt complexes have been already described. - Dibenzo-18-crown-6 polyether is useful for the preparation of sharpmelting salt complexes. Dicyclohexyl-18-crown-6 polyether has the convenient property of solubilizing sodium and potassium salts in aprotic solvents, as exemplified by the formation of a toluene solution of the potassium hydroxide complex (Note 13). Crystals of potassium permanganate, potassium Lbutoxide, and potassium palladium(II) tetrachloride (PdClj + KCl) can be made to dissolve in liquid aromatic hydrocarbons merely by adding dicyclohexyl-18-crown-6 polyether. The solubilizing power of the saturated macrocyclic polyethers permits ionic reactions to occur in aprotic media. It is expected that this [)ropcrty will find practical use in catalysis, enhancement of... 

The electronic301 and magnetic properties of mononuclear chromium(III) complexes are quite well understood however there is a distinct tendency for octahedral symmetry to be invoked in cases where the true symmetry is much lower. Chromium(III) is a hard Lewis acid and many stable complexes are formed with oxygen donors. In particular hydroxide complexes are readily formed in aqueous solution, and this may be a problem in synthesis. Substitution at chromium(III) centres is slow302,303 and may well have some associative character in many cases. The kinetic inertness of chromium(III) has led to the resolution of many optically active complexes this work has been extensively reviewed.304... 

Pokrovski, G., Gout, R., Schott, J. et al. (1996) Thermodynamic properties and stoichiometry of As(III) hydroxide complexes at hydrothermal conditions. Geochimica et Cosmochimica Acta, 60(5), 737-49. 

In light of the accepted mechanism for cytochrome P-450 (97-100), a superoxo-Cu(II) intermediate is further reduced, leading to dioxygen activation. Accordingly, a monomeric peroxo or hydroperoxo copper(II) complex serves as a synthetic model for these intermediates of copper-containing monooxygenases. However, no well-characterized complexes of these types are available to date. Formation of a monomeric hydroperoxo or acylperoxo complex was reported to occur when a trans-/u-l,2-peroxo complex, [(Cu(TPA))2(02)]z+, was treated with H+ or RC(O)+, but no details of the structures and properties of the complexes were provided (101). A related complex, a monomeric acylperoxo cop-per(II) complex, was synthesized (102). Low-temperature reaction of a dimeric copper(II) hydroxide complex, [Cu(HB(3,5-iPr2pz)3)]2(OH)2, with 2 equivalents of m-CPBA (3-chloroperoxybenzoic acid) yielded a monomeric acylperoxo complex whose structure was characterized by... 

Amphoteric Hydroxides. A hydroxide, such as zinc hydroxide, which can combine with acids to form salts and also with bases to form salts is called an amphoteric hydroxide. The amphoteric properties of a metal hydroxide are determined by the stability of the hydroxide complex of the metal. 

The hydroxides listed above form hydroxide complex anions to a sufficient extent to make them soluble in moderately strong alkali. Other common hydroxides have weaker acidic properties Cu(OH). and Co(OH), are only slightly soluble in very strong alkali, and Cd(OH) >, Fe(OH)3, Mn(OH)j, and Ni(OH) are effectively insoluble. The common analytical method of separation of A1+ + +, Cr+ ++, and Zn++ from Fe+ ++, Mn+ +, Co+ +, and Ni++ with use of sodium hydroxide is based on these facts. 

Most of the recent experimental work on the detailed thermodynamic properties of thorium compounds has been on solubilities and aqueous solutions. The large number of hydroxide complexes of Th(IV) and the propensity to form colloidal solutions, makes the interpretation of these studies a challenging task. As noted in previous reviews, the development of laser-based spectroscopic techniques has been a useful tool in our increased understanding of these phenomena, and it is gratifying that... 

The hydroxides listed above form hydroxide complex anions to a sufficient extent to make them soluble in moderately strong alkali. Other common hydroxides have weaker acidic properties Cu(OH)2 and... 

Pillared clay - Pillared clay is purified smectite, usually montmorillonite, treated in an aqueous dispersion with large metal hydroxide complexes (e g., almninum chlorohydrate), dried, partially calcined, and milled. The metal complexes form dmable pillars between clay platelets, maintaining a fixed, well defined separation between them. Because of their size- and shape-selective absorption properties, pillared clays share certain molecular sieve appHcations with zeohtes. 

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