Complex ions defined

Polytungsta.tes, An important and characteristic feature of the tungstate ion is its abiUty to form condensed complex ions of isopolytungstates in acid solution (38). As the acidity increases, the molecular weight of the isopolyanions increases until tungstic acid precipitates. However, the extensive investigations on these systems have been hampered by lack of weU-defined soHd derivatives. 

S Tantalum and niobium are present in the crystal structure in the form of complex ions. The lowest coordination number, 6, corresponds to the formation of slightly distorted octahedrons. The linking and packaging of the octahedrons depends on the X Me ratio, where X is the total number of oxygen and fluorine atoms, and Me is the total number of tantalum or niobium ions as well as other metals that can replace tantalum or niobium in the octahedral polyhedron. The crystal structure type can be defined based on the X Me ratio, as follows ... 

Complex ions, also called coordination complexes, have well-defined stoichiometries and structural arrangements. Usually, the formula of a coordination complex is enclosed in brackets to show that the metal and all its ligands form a single structural entity. When an ionic coordination complex is isolated from aqueous solution, the product is composed of the complex ion and enough counter-ions to give a neutral salt. In the chemical formula, the counter-ions are shown outside the brackets. Examples include the sulfate salt of [Ni (NH3)g, ... 

The sections are divided by the coordination number of the reacting ion defined as the number of donor atoms that interact with the metal. The nomenclature used for the ligands is L for neutral molecules that act as ligands and X for anions that act as ligands. Most of the examples in this section will involve cations [ML ]+ or [MX ]+, but there will be a short section on bare metal anions, M . The anions of more complexity than M will be discussed in Section IV on clusters. Many reactions produce an initial product that continues to react resulting in further coordi-native changes and possibly redox changes. Tables I and II will indicate the initial reaction product and other major reaction products. 

Define monodentate, bidentate, hexadentate, ligand, complex ion, chelate, chelating agent, masking, masking agent, formation constant, coordinate covalent bond, water hardness, aliquot. 

Define ligand and complex ion. Give an example of each. 

The molar ratio of the excess amount of Ag+ (defined by AAg) to that of RS ions(defined by ARS) are dose to unity in all the samples, indicating that the side reaction [Eq. (6)] and then its product RSAg should be taken into account to interpret the data of elemental analysis. This RSAg molecular complex was found to be amorphous by XRD observation. It was also found that a particle with a size of 15 nm was almost free from RSAg by comparing the content of empirical formula with that of the theoretical one in Table 4,4.3. The RSAg complex cannot be removed in the present procedure for smaller particles whose size is less than 10 nm due to its small A sp value, but one can eliminate it by a careful control of the pH of suspensions. 

Jote the greater complexity of defining adsorption here in studies of electric double layers than, e.g., for metal-gas systems. With electric double layers, one is concerned with the whole interphasial region. The total adsorption is the sum of the increases of concentration over a distance, which in dilute solutions may extend for tens of nanometers. Within this total adsorption, there are, as will be seen, various types of adsorptive situations, including one, contact adsorption, which counts only Arose ions in contact with the electronically conducting phase (and is Aren, like the adsorption referred to in metal-gas systems, the particles on Are surface). Metal-gas systems deal with interfaces, one might say, whereas metal-electrolyte systems deal primarily with interphases and only secondarily with interfaces. 

Formation constants are the equilibrium constants for complex ion formation. The stepwise formation constants, designated K, are defined as follows ... 

Equilibria in the formation of complex ions with metals are treated exactly as is the binding of small molecules and ions to macromolecules.87-89 Stepwise constants are defined for the formation of complexes containing one, two, or more ligands L bound to a central metal ion M. The binding constants K/s are usually referred to as P s as in Eq. 6-84. 

PK. A measurement of the complete ness of an incomplete chemical reaction. It is defined as the negative logarithm ito the base 101 of the equilibrium constant K for the reaction in question. The pA is most frequently used to express the extent of dissociation or the strength of weak acids, particularly fatty adds, amino adds, and also complex ions, or similar substances. The weaker an electrolyte, the larger its pA. Thus, at 25°C for sulfuric add (strong acid), pK is about -3,0 acetic acid (weak acid), pK = 4.76 bone acid (very weak acid), pA = 9.24. In a solution of a weak acid, if the concentration of undissociated acid is equal to the concentration of the anion of the acid, the pAr will be equal to the pH. 

The magnetic susceptibility is thus a temperature-dependent property of a bulk substance. It is meaningless to specify the susceptibility of a single molecule or complex ion. For convenience, inorganic chemists prefer to answer the question How paramagnetic is this substance in terms of the magnetic moment peff defined by the relation ... 

It has been proposed that there may be a close link between the amount of an element available to living matter and the fraction of the total content which is labile (with the lability value being loosely defined as the total, accessible, hydrated ion level). Either the whole or part of the analytical result may be derived from dissociation of labile complex ions or dissolution of moderately soluble compounds. If one or both of these two processes proceed at a relatively slow rate, the magnitude of the lability value becomes time dependent . Conversely, if a complex exchanges ligands fairly rapidly, the amount present in... 

In aqueous solutions, the situation is clarified by the solvent. This solvent keeps the complex ions apart at mean distances, defines them as independent stable entities, and permits probing radiation (e.g., visible light) to pick them out from the surroundings (Fig. 5.5). 

Chiral separations generally rely on the formation of transient diastereomeric complexes with differing stabilities. Complexes are defined as two or more compounds bound to one another in a definite structural relationship by forces such as hydrogen bonding, ion pairing, metal-ion-to-ligand attraction, n-acid/ n-base interactions, van der Waals attractions, and entropic component desolvation. In the following sections, the most important types of molecular interactions in chiral separations are discussed. 

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