Anions containing metal atoms

TABLE 22.5 Names of Anions Containing Metal Atoms... 

If the complex is an anion, its name ends in -ate. For example, in K4[Fe(CN)6] the anion [FeCCN) ]" " is called hexacyanoferrate(II) ion. Note that the Roman numeral II indicates the oxidation state of iron. Table 22.5 gives the names of anions containing metal atoms. 

Strategy We follow the procedure in Section 22.3 of the text and refer to Tables 22.4 and 22.5 of the text for names of ligands and anions containing metal atoms. 

While flame photometry could be used for the determination of complex anions containing metals (although for the most part anions are nuisances at best in this technique), the companion technique of atomic absorption has been applied to selenium by Rann and Hambly (22). They have determined selenium in the 10 to 100 p.p.m. range, using the 2040 A. 3S 3P transition and a propane-air flame. 

The crystal structure of the silver(i) salt of the antibiotic X-537A (105) contains dimeric units in which two silver ions are encapsulated by two organic anions. Each metal atom bonds to an aromatic multiple bond in... 

These hydrated salts contain bidentate carbonate ligands and no water molecules are bound directly to the central metal atom. The only single-crystal x-ray diffraction studies available are those for salts of (4) (52—54) and the mineral tuliokite [128706 2-3], Na2BaTh(C03)2 -6H20], which contains the unusual Th(C02) 2 anion (5) (55). 

In principle, any molecule or anion with an unshared pair of electrons can act as a Lewis base. In other words, it can donate a lone pair to a metal cation to form a coordinate covalent bond. In practice, a ligand usually contains an atom of one of die more electronegative elements (C, N, O, S, F, Cl, Br, I). Several hundred different ligands are known. Those most commonly encountered in general chemistry are NH3 and HzO molecules and CN , Cl-, and OH- ions. 

Halogens, the elements in Group 17 of the periodic table, have the largest electron affinities of all the elements, so halogen atoms (a n readily accept electrons to produce halide anions (a a. This allows halogens to react with many metals to form binary compounds, called halides, which contain metal cations and halide anions. Examples include NaCl (chloride anion), Cap2 (fluoride anion), AgBr (bromide anion), and KI (iodide anion). 

Electrodes of the second kind. These electrodes consist of three phases. The metal is covered by a layer of its sparingly soluble salt, usually with the character of a solid electrolyte, and is immersed in a solution containing the anions of this salt. The solution contains a soluble salt of this anion. Because of the two interfaces, equilibrium is established between the metal atoms and the anions in solution through two partial equilibria between the metal and its cation in the sparingly soluble salt and between the anion in the solid phase of the sparingly soluble salt and the anion in solution (see Eqs (3.1.24), (3.1.26) and (3.1.64)). 

---