Additive nomenclature coordination compounds

This overview covers some of the rules for naming simple inorganic compounds. There are additional rules, and some exceptions to these rules. The first part of this overview discusses the rules for deriving a name from a chemical formula. In many cases, the formula may be determined from the name by reversing this process. The second part examines situations in which additional information is needed to generate a formula from the name of a compound. The transition metals present some additional problems therefore, there is a section covering transition metal nomenclature and coordination compounds. 

This system is additive and was developed originally to name coordination compounds, although it can be used in other circumstances when appropriate. For a discussion, see the Nomenclature of Inorganic Chemistry, Chapter 10. The compound to be named is considered as a central atom together with its ligands, and the name is developed by assembling the individual names of the constituents. This system has also been applied to name oxoacids and the related anions. Coordination names for oxoanions are cited in the examples throughout the text, and they are presented in detail in Section 4.4.5 (p. 69). 

Coordination nomenclature, an additive nomenclature. According to a useful, historically-based formalism, coordination compounds are considered to be produced by addi-... 

Coordination nomenclature. This is an additive system for inorganic coordination compounds which treats a compound as a combination of A central atom wiih associated ligands (see Section 1-10). 

Generally, nomenclature systems use a base on which the name is constructed. This base can be derived from a parent compound name such as sil (from silane) in substitutive nomenclature (mainly used for organic compounds) or titan a central atom name such as cobalt in additive nomenclature (mainly used in coordination chemistry). 

Nomenclature before Werner (to 1897)- The Lavoisierian system of nomenclature, even with the Berzelius modifications, provided no suitable names for that class of compounds which later was designated coordination compounds. Names based on the patterns for double salts and addition compounds were not satisfactory because the properties of these materials were not those consistent with the patterns provided. Consequently, names based on properties, especially color (Table I), or the names of prominent investigators became popular (2) because they, at least, did not commit the user to any theory of their structure. The developments in organic chemistry after 1860 did not contribute to the understanding of these strange compounds, so there was no carry-over to them of the nomenclature developments in organic chemistry. 

IR-1.5.3.2 Compositional nomenclature IR-1.5.3.3 Substitutive nomenclature IR-1.5.3.4 Additive nomenclature IR-1.5.3.5 General naming procedures IR-1.6 Changes to previous IUPAC recommendations IR-1.6.1 Names of cations IR-1.6.2 Names of anions IR-1.6.3 The element sequence of Table VI IR-1.6.4 Names of anionic ligands in (formal) coordination entities IR-1.6.5 Formulae for (formal) coordination entities IR-1.6.6 Additive names of polynuclear entities IR-1.6.7 Names of inorganic acids IR-1.6.8 Addition compounds IR-1.6.9 Miscellaneous... 

Along with the theory of coordination, Werner proposed5 a system of nomenclature for coordination entities which not only reproduced their compositions but also indicated many of their structures. Werner s system was completely additive in that the names of the ligands were cited, followed by the name of the central atom (modified by the ending ate if the complex was an anion). Wemer also used structural descriptors and locants. The additive nomenclature system was capable of expansion and adaptation to new compounds and even to other fields of chemistry. 

Additive nomenclature treats a compound or species as a combination of a central atom or central atoms with associated ligands. The particular additive system used for coordination compounds (see Chapter IR-9) is sometimes known as coordination nomenclature although it may be used for much wider classes of compounds, as demonstrated for inorganic acids (Chapter IR-8) and organometallic compounds (Chapter IR-10) and for a large number of simple molecules and ions named in Table IX. Another additive system is well suited for naming chains and rings (Section IR-7.4 see Example 6 below). 

The designation of central atom and ligands, generally straightforward in mononuclear complexes, is more difficult in polynuclear compounds where there are several central atoms in the compound to be named, e.g. in polynuclear coordination compounds, and chain and ring compounds. In each case, a priority order or hierarchy has to be established. A hierarchy of functional groups is an established feature of substitutive nomenclature Table VI shows an element sequence used in compositional and additive nomenclature. 

There is no difference between donor-acceptor complexes and coordination compounds from a nomenclature point of view. Thus, for such systems an additive name such as described in Sections IR-7.1 to IR-7.3 and in Chapter IR-9 may be given. 

Additive nomenclature was originally developed for Werner-type coordination compounds, which were regarded as composed of a central atom (or atoms) surrounded by added groups known as ligands, but many other types of compound may also be conveniently given additive names. Such names are constructed by placing the names of the ligands (sometimes modified) as prefixes to the name(s) of the central atom(s). 

The compound commonly named diphosphoric acid, H4P2O7 = [(H0)2P(0)0P(0)(0H)2], is named according to the coordination-type additive nomenclature as ... 

IR-9.1.2.9 Coordination nomenclature an additive nomenclature IR-9.1.2.10 Bridging ligands IR-9.1.2.11 Metal-metal bonds IR-9.2 Describing the constitution of coordination compounds IR-9.2.1 General... 

This Chapter presents the definitions and rules necessary for formulating and naming coordination compounds. Key terms such as coordination entity, coordination polyhedron, coordination number, chelation and bridging ligands are first defined and the role of additive nomenclature explained (see also Chapter IR-7). 

Recognition of the relationships between these complex compounds led to the formulation of coordination theory and the naming of coordination compounds using additive nomenclature. Each coordination compound either is, or contains, a coordination entity (or complex) that consists of a central atom to which other groups are bound. 

The nomenclature of coordination chemistry has changed over time. The older literature features multiple nomenclature styles. Contemporary rules used for naming coordination compounds are discussed in this chapter. More complete sources are available to explore classic nomenclature approaches necessary to examine older literature and additional nomenclature schemes not covered in this introductory section. ... 

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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