Names of formal addition compounds

The term addition compounds covers donor-acceptor complexes (adducts) and a variety of lattice compounds. The method described here, however, is relevant not just to such compounds, but also to multiple salts and to certain compounds of uncertain structure or compounds for which the full structure need not be communicated. 

For addition compounds containing water as a component, the class name hydrates is acceptable because of well established use, even though the ending ate might seem to indicate an anionic component. For hydrates with a simple stoichiometry, names of the classical hydrate type are acceptable, but rules have not been formulated for non-integer stoichiometries such as that in Example 12 below. Also, because of their ambiguity, the 

BiCl3-3PCl5 bismuth(III) chloride— phosphorus)V) chloride (1/3) 

2Na2C03-3H202 sodium carbonate—hydrogen peroxide (2/3) 

Na2SO4T0H2O sodium sulfate—water (1/10), or sodium sulfate decahydrate 

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The solidus (/) is used in names of formal addition compounds to separate the arabic numerals which indicate the proportions of individual constituents in the compound. 

IR-5.4.2.3 Multiple monoatomic constituents vs. homopolyatomic constituents IR-5.5 Names of (formal) addition compounds IR-5.6 Summary IR-5.7 References... 

The radical and the anion, R-N2 and R-N2, derived (formally) from a diazonium ion by addition of one and two electrons respectively, are named as diazenyl ( radical at the end is not necessary ) and diazenide (IUPAC, 1993). The radical derived formally from a diazoalkane by addition of a hydrogen atom (R=N-NH) is named diazanyl . In order to be consistent with the nomenclature of diazonium ions, the name of the parent compound should precede the words mentioned, e. g., benzenediazenyl for C6H5 - NJ (the term phenyldiazenyl radical is, however, used by Chemical Abstracts). 

A problem arises with trivial names when a sp hybridized atom is present in an otherwise unsaturated ring. A good example is pyran, a heterocycle that is formally the product of the addition of a single hydride ion to the pyrylium cation. However, as this addition could occur either at C-2 or C-4, two isomers of pyran are possible so the question is, how can you distinguish between them The solution is to call one compound 2/f-pyran and the other 4/f-pyran, using the number of the ring atom and the letter H, in italics, to show the position of the hydrogen (see Box 1.2). This system of nomenclature works tolerably well in many related cases and is widely used other examples will be found in this book. 

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... 

The formalism for addition compounds, and other compounds treated as such, has been rationalized (see Sections IR-4.4.3.5 and IR-5.5) so as to remove the exceptional treatment of component boron compounds and to make the constmction of the name self-contained rather than dependent on the formula. Thus, the double salt carnallite, when considered formally as an addition compound, is given the formula ... 

For chain compounds containing three or more different elements, the sequence of atomic symbols should generally be in accord with the order in which the atoms are bound in the molecule or ion, rather than using alphabetical order or order based on electronegativity. However, if one wishes to view a compound formally as a coordination compound, e.g. in connection with a discussion of additive naming of the compound, one may use a coordination-compound type of formula, as in Example 1 below. 

Aldehydes are formally named by changing the final -e of the name of the alkane with the same number of carbon atoms to the suffix -a/. Thus, the formal name of the compound methanal, shown in Table 22.7, is based on the one-carbon alkane methane. Because the carbonyl group in an aldehyde always occurs at the end of a carbon chain, no numbers are used in the name unless branches or additional functional groups are present. Methanal is also commonly called formaldehyde. Ethanal has the common name acetaldehyde. Scientists often use the common names of organic compounds because they are familiar to chemists. 

A significant international effort, resulting in the set of rules collectively known as those of the International Union of Pure and Applied Chemistry (lUPAC, Chapter 3) has already been put forth to systematize the names of organic compounds. These rules will be followed here, but trivial (or common) names will also be used because they remain current. In addition to formal nomenclature, it is often convenient to distinguish or signify a particular carbon (or carbons) generically because of, for example, similarities in behavior. There are several ways to do this. 

This Table gives acceptable common names, functional replacement names (see Section IR-8.6) and systematic (additive) names for compounds related to oxoacids in Table IR-8.1 and certain isomers and corresponding anions. The examples given are derived by formal replacement of an O atom/O atoms, or of an OH group/OH groups, by (an)other atom(s) or group(s). 

The LMTO method has the computational speed and flexibility needed to perform calculations of electron states in molecules and compounds. Therefore in the present chapter we shall generalise the LMTO formalism purely within the atomic-sphere approximation to include the case of many inequivalent atoms per cell. The LMTO method is based on the variational principle in conjunction with energy-independent muffin-tin orbitals but, in addition to this approach, we have also considered the tail-cancellation principle which led to the KKR-ASA condition (2.8). Since the latter has conceptual advantages, we apply the tail-cancellation principle to the simplest possible case of more than one atom, namely the diatomic molecule. After that, we turn to crystalline solids and generalise or sometimes rederive the important equations of LMTO formalism. Hence, in addition to giving the LMTO equations for many atoms per cell, the present chapter may also serve as a short and compact presentation of the crystal-structure-dependent part of LMTO formalism. The potential-dependent part is treated in Chap.3. In the final sections are listed the modifications needed to calculate ground-state properties for materials with several atoms per cell. 

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