Naming Coordination Complexes

Cations are named before anions (similar to ionic materials). 

The naming of the central metal atom depends on the charge. If it s a negatively charged metal, the anion is given the suffix -ate, such as col-baltate, zincate, sulphate. But if the metal is either neutral or positively charged, it s just named as the element. 

The oxidation state of the metal atom has to be shown it s written as a Roman numeral inside parentheses (IV), for example. 

There s the possibility of having more than one metal atom present. These are called polynuclear atoms, and the ligand bridging the metal atoms is indicated by the prefix -p. 

K3[Fe(CN)g] Potassium is the cation, so it s named first. There are six cyanide ligands that are each anionic so it s referred to as hexacyano. 

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An abbreviated, simple set of rules for naming coordination complexes follows. The complete set of rules for nomenclature is very extensive. 

It was assumed that tantalum, when added to the melt in the form of potassium heptafluorotantalate, K2TaF7, interacts with KF or KC1 to form a compound with an increased tantalum coordination number of up to eight. The compound is present in the melt in its dissociated form, yielding potassium ions and octa-coordinated complexes of tantalum, namely TaFg3 or TaF7Cl3. ... 

HOWTO NAME (/-METAL COMPLEXES AND COORDINATION COMPOUNDS... 

Originally, compounds containing coordination complexes were given common names such as Prussian blue (KFe[Fe (CN)g ]), which is deep blue, or Reinecke s salt (NH4[Cr (NH3)2 (NCS)4]), named for its first maker. Eventually, coordination compounds became too numerous for chemists to keep track of all the common names. To solve the nomenclature problem, the International Union of Pure and Applied Chemistry (lUPAC) created a systematic procedure for naming coordination compounds. The following guidelines are used to determine the name of a coordination compound from its formula, or vice versa ... 

If the coordination complex is an anion, add the suffix -ate to the stem name of the metal. 

Follow the guidelines for naming coordination compounds. Break the complex ion down one piece at a... 

The first and third examples illustrate a nuance of the naming rules. Iron and silver in anionic complexes are named by their Latin roots,/err- and argent-, from which their symbols (Fe and Ag) are derived. Metals taking their Latin names in anionic coordination complexes are listed in Table 20-4. 

In 2005, Carretero et al. reported a second example of chiral catalysts based on S/P-coordination employed in the catalysis of the enantioselective Diels-Alder reaction, namely palladium complexes of chiral planar l-phosphino-2-sulfenylferrocenes (Fesulphos). This new family of chiral ligands afforded, in the presence of PdCl2, high enantioselectivities of up to 95% ee, in the asymmetric Diels-Alder reaction of cyclopentadiene with A-acryloyl-l,3-oxazolidin-2-one (Scheme 5.17). The S/P-bidentate character of the Fesulphos ligands has been proved by X-ray diffraction analysis of several metal complexes. When the reaction was performed in the presence of the corresponding copper-chelates, a lower and opposite enantioselectivity was obtained. This difference of results was explained by the geometry of the palladium (square-planar) and copper (tetrahedral) complexes. 

The number of rules that need to be followed in naming coordination compounds is small, but they are sufficient to permit naming the majority of complexes. The rules will be stated and then illustrated by working through several examples. 

A complex may be ionic or neutral. An ionic complex is called a complex ion. A neutral complex is a type of coordination compound. The only difference in naming coordination compounds or complex ions is that anionic complex ions have an ate suffix. 

When the coordination complex is destroyed, no azo coupling takes place. In this case, only electron transfer products are formed, namely, o-dinitrobenzene, a benzene derivative RCgH from RCgH4N2BF4, gaseous nitrogen, and KBF4. 

In this section, we have discussed in detail only one class of carbonyls, namely monosubstituted octahedra. More highly substituted octahedra have been less thoroughly investigated, either because the CO parameter analysis is less certain, or because the separation of ligand cis- and imns-influences is less clearcut. In substituted tetrahedra, the distinction between cis and trans CO groups does not exist, while in 5-coordinate complexes, the situation is further complicated, quite apart from the effects of substituents, by the axial-equatorial distinction. 

Under general headings such as Cobalt(III) complexes and Ammines, used for grouping coordination complexes of similar types having names considered unsuitable for individual headings, formulas or names of specific compounds are not usually given. Hence it is imperative to consult the Formula Index for entries for specific complexes. 

It should be noted that the word complex , often used in supramolecular chemistry, is not very specific. It is applied to charge-transfer complexes like the one formed by 21 with 22 [30] as well as to coordination complexes consisting of one or more atoms or ions with n ligands like K2[Pt(N02)4]. The same name complex also covers the Whitesides hydrogen bonded systems [10] shown in Figure 1.1 and inclusion complexes of 4 embedded in 5. Thus the term complex without any adjective has no specificity and can be applied to any type of molecular associates. 

Coordination cations. The names of complex cations are derived most simply by using the coordination cation names (see Section I—10). This is preferred whenever umbigu-ity might result. 

The number of ligand donor atoms bonded to a metal is called the coordination number of the metal. Common coordination numbers and geometries are 2 (linear), 4 (tetrahedral or square planar), and 6 (octahedral). Systematic names for complexes specify the number of ligands of each particular type, the metal, and its oxidation state. 

Addition polymerization may be propagated by three distinct types of reactive centers, namely, radicals, ions, or coordination complexes,... 

In C-coordinated complexes, the frequency splitting between the two v(CO) stretching modes is less than 400 cm-1, and in end-on complexes, the out-of-plane bending mode y(C=0), located in the 500-650cm-1 region, exhibits a preponderant lsO effect, in contrast with other coordination modes, where a larger 13C effect is observed (namely Ay(13C) = 10 to 20cm-1, versus Ay(180) = 5 cm-1). 

The names of anions usually end in -ide if there are monatomic or homopolyatomic, or -ate for heteropolyatomic anions and coordination compounds. Anionic ligands usually end in -o. Thus CP is chloride, I3 is triiodide and S042 is sulfate but become, chloro, triiodo and sulfato if they are coordinated as ligands. The names of complex anions are not always derived from the familiar name... 

It is worth to mention that both coordination compounds, namely [Ca(7)2]DBTA and [Ca(H20)](12)DBTA form conglomerates with their enantiomers, respectively. Thus, optical resolution of racemic DBTA by preferential crystallization of these coordination complexes is also possible. [26, 27]... 

Naming of Coordination Sphere In naming the complex, the names of the ligands are written first followed by the name of the central ion. The oxidation number of the central metal atom is expressed by Roman numeral in parentheses just after the name of the central metal atom. The sequence of naming coordination sphere is summed up as ... 

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