Names of complex ions

Coordina- tion Number Shape Ligand Structure/Formula Name of complex ion/neutral complex... 

Write the name of complex ions and coordination compounds. 

Nomenclature of complex ions and organic compounds. We believe that this material is of little value in a beginning course. The students promptly forget how to name a complex ion, because they have litde chance to use the rules. The naming of organic compounds seems better left to a course in organic chemistry. 

An investigation of the physical-chemical properties and IR spectra of melts with relatively low metal concentrations indicated that heptafluorometalate ions, TaF72, are also present in the melt. These measurements initiated the second conceptual step and it was assumed that there are two types of complex ions, namely octafluorometalate, MeF83 , and heptafluorometalate, MeF72, that determine the melt s various properties. 

Table 55 presents the results discussed above. Fluoride melts containing tantalum contain two types of complex ions, namely TaF6 and TaF72 . The equilibrium between the complexes depends on the concentration of fluoride ions in the system, but mostly upon the nature of the outer-sphere cations. The complex ionic structure of the melts can be adjusted by adding cations with a certain polarization potential. For instance, the presence of low polarization potential cations, such as cesium, leads primarily to the formation of TaF72 complexes, while the addition of cations with relatively high polarization potentials, such as lithium or sodium, shifts the equilibrium towards the formation of TaF6 ions. 

In naming a complex ion, the ligands are named in alphabetical order. A prefix that is used to indicate the number of ligands is not considered as part of the name of the ligand. For example,... 

For multistep complexation reactions and for ligands that are themselves weak acids, extremely involved calculations are necessary for the evaluation of the equilibrium expression from the individual species involved in the competing equilibria. These normally have to be solved by a graphical method or by computer techniques.26,27 Discussion of these calculations at this point is beyond the scope of this book. However, those who are interested will find adequate discussions in the many books on coordination chemistry, chelate chemistry, and the study and evaluation of the stability constants of complex ions.20,21,28-30 The general approach is the same as outlined here namely, that a titration curve is performed in which the concentration or activity of the substituent species is monitored by potentiometric measurement. 

Q The name of the complex ion, whether it is an anion, cation, or neutral, is written as two parts that are combined into one word. The first part consists of the name of the ligand, and the second part, the name of the metal ion. If more than one of the same type of ligand appears, Greek prefixes are used to indicate the number of times the ligand occurs. A Roman numeral is used to indicate the charge on the cation. For instance, the name of the ion in the previous example, Fe(CN)64, is hexacyanofer-rate (II) ion. 

Q In a complex ion or molecule, if more than one type of ligand appears, the order of appearance is determined alphabetically. For example, the complex ion Pt(NH3)4Cl22+ contains two ligands, NH3 and Cl-. The name of the ion is tetraam-minedichloroplatinum (IV) ion. 

From these examples the rules of nomenclature are apparent. The central atom (like Fe, Cu, Co, Ag) is followed by the formula of the ligand (CN, NH3, H20, S203), with the stoichiometric index number, (which, in the case of monodentate ligands is equal to the coordination number). The formula is placed inside square brackets, and the charge of the ion is shown outside the brackets in the usual way. When expressing concentrations of complexes, brackets of the type will be used to avoid confusion. In the name of the ion, first the (Greek) number, then the name of the ligand is expressed, followed by the name of the central atom and its oxidation number (valency). 

Write formulas for two complex ions that would fit into each of the categories of Exercise 37. Name the complex ions you list. 

Since a good deal of the pioneering work on equilibria of complex ions was carried out in Sweden and Denmark, Joseph thought it would be a good idea to visit and talk with some of the people there who were known to us only as names. I was pleased when Joseph asked me to accompany him. We had an enjoyable and fruitful trip in June of 1952. We were fortunate to meet both Bjerrums (Nils and Jannik), Kai Jensen (who had done early studies of tertiary phosphine, arsine... 

Structures of Complex Ions Formulas and Names Isomerism... 

Be familiar with the coordination numbers, geometries, and ligands of complex ions name and write formulas for coordination... 

A coordination compound is an electrolyte in water the complex ion and counter ions separate, but the complex ion behaves like a polyatomic ion because the ligands and central metal ion remain attached. Thus, as Figure 22.7A shows, 1 mol of [Co(NH3)g]Cl3 yields 1 mol of [Co(NH3)g] ions and 3 mol of Cl ions. This section covers the structure, naming, and properties of complex ions. 

The oxidation state of the metal ion has a Roman numeral (in parentheses) only if the metal ion can have more than one state. Since cobalt can have +2 and +3 states, we add a in to name the complex ion. Thus, the compound is... 

Be familiar with the coordination numbers, geometries, and ligands of complex ions name and write formulas for coordination compounds describe the types of constitutional and stereoisomerism they exhibit ( 22.2) (SPs 22.2, 22.3) (EPs 22.18-22.39)... 

Name the complex ion by adding prefixes to indicate the number of each ligand followed by the name of each ligand followed by the name of the metal ion. [Cr(H20)5Cl]2+is pentaaquachlorochromium(ni). [Fe(CN)6l is hexacyanoferrate(III). 

In naming coordination compounds, we use the name of the cation followed by the name of the anion. To name a complex ion we use the guidelines outlined in Section 24.3. 

Since the lUPAC nomenclature system relies totally on the pivotal concept of the parent structure to which, in a second sphere, substituents are assigned, it appeared advisable to maintain this division also for the chapters of this book. Thus, we begin with the exposition of the nomenclature rules for parent structures and, in the second chapter, proceed with the discussion of the different types of nomenclature for substituted systems, radicals, and ions in the third chapter specific classes of functional compounds are addressed, followed, in the forth chapter, by the treatment of metal organyls and, in the fifth, of carbohydrates. The concluding sixth chapter takes up once again the construction of the final names of complex compounds including isotopic modifiers and stereochemical descriptors. 

In molecular crystals or in crystals composed of complex ions it is necessary to take into account intramolecular vibrations in addition to the vibrations of the molecules with respect to each other. If both modes are approximately independent, the former can be treated using the Einstein model. In the case of covalent molecules specifically, it is necessary to pay attention to internal rotations. The behaviour is especially complicated in the case of the compounds discussed in Section 2.2.6. The pure lattice vibrations are also more complex than has been described so far . In addition to (transverse and longitudinal) acoustical phonons, i.e. vibrations by which the constituents are moved coherently in the same direction without charge separation, there are so-called optical phonons. The name is based on the fact that the latter lattice vibrations are — in polar compounds — now associated with a change in the dipole moment and, hence, with optical effects. The inset to Fig. 3.1 illustrates a real phonon spectrum for a very simple ionic crystal. A detailed treatment of the lattice dynamics lies outside the scope of this book. The formal treatment of phonons (cf. e(k), D(e)) is very similar to that of crystal electrons. (Observe the similarity of the vibration equation to the Schrodinger equation.) However, they obey Bose rather than Fermi statistics (cf. page 119). 

When naming complex ions the number and type of ligands is written first, followed by the name of the central metal ion. If the complex as a whole has a positive charge, i.e. a cation, the name of the central metal is written unchanged and followed by the oxidation state of the metal in brackets, for example [Cu(N 113)4] becomes tetra-ammine copper(II). A similar procedure is followed for anions but the suffix -ate is added to the central metal ion some examples are ... 

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