Complexes coordination-type nomenclature

Fig. 2. Classification/nomenclature of host—guest type inclusion compounds, definitions and relations (/) coordinative interaction, (2) lattice barrier interaction, (J) monomolecular shielding interaction (I) coordination-type inclusion compound (inclusion complex), (II) lattice-type inclusion compound (multimolecular/extramolecular inclusion compound, clathrate), (III) cavitate-type inclusion compound (monomolecular/intramolecular inclusion...

VI (d2), and the examples in Table 1 illustrate the kinds of complexes formed and their stereochemistries. Several of these oxidation states are not well characterized the — I and V states are rare, while I is not common. The most frequently encountered oxidation states in complexes of a conventional coordination type (particularly in aqueous media) are II (ds) and III (ds) the ferrous and ferric states respectively. The preferred nomenclature, and that used here, indicates these oxidation states as iron(II) and iron(III). 

The separation of coordination compounds into four types, as described above (a) encompasses practically all types of complexes reported in modern coordination chemistry [1,2,10,16,34,124-127] (b) is clear and informative with respect to a given molecule in a coordination compound as a whole, and does not rely on its individual portions (c) concentrates its attention on the special features of some types of metal complexes (d) follows from the modern approach to study the structures of metal complexes [16,34,125,126], together with their systematic nomenclature [122,123]. 

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). 

Polynuclear inorganic complexes exist in a bewildering array of structural types, such as ionic solids, molecular polymers, extended assemblies of oxoanions, chains and rings, bridged metal complexes, and homonuclear and heteronuclear clusters. This section primarily treats the nomenclature of bridged metal complexes and homonuclear and heteronuclear clusters. Coordination polymers are treated extensively elsewhere.6... 

During Werner s time compositional nomenclature for binary compounds had already been agreed upon in much the same way as today, and names such as manganese dichloride and manganese monooxide were in common use to express information about stoichiometric compositions only. For complex compounds, this type of nomenclature had simply b n extended as in the notational example 3 KCN,Fe(CN)3. Werner realized that diis notation could be modified to became a nomenclature including structural information, when this was available, and potassium hexacyanoferriate is his ingenious proposal (2). This is an example of what is today referred to as additive nomenclature or coordination nomenclature, as opposed to the substitutional nomenclature of organic chemistry. 

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