Page 25 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

G R A M M A R I R-2.1

IR-2.15 O rdering principles
IR-2.15.1 Introduction
IR-2.15.2 Alphabetical order
IR-2.15.3 Other ordering r ules
IR-2.15.3.1 Element ordering on the basis of the periodic table
IR-2.15.3.2 Ordering of parent hydrides
IR-2.15.3.3 Ordering characteristic groups for substitutive nomenclature
IR-2.15.3.4 Ordering ligands in formulae and names
IR-2.15.3.5 Ordering components in salt formulae and names
IR-2.15.3.6 Isotopic m odification
IR-2.15.3.7 Stereochemical priorities
IR-2.15.3.8 Hierarchical ordering o f p unctuation marks
IR-2.16 F inal remarks
IR-2.17 R eferences

IR-2.1 I N T R O D U C T I O N

Chemical n omenclature may be considered to be a l anguage. As such, it consists of words
and it should o bey the rules of syntax.
In the language of chemical nomenclature, the simple names of atoms are the words. As
words are assembled to form a s entence, s o n ames of atoms are assembled to form names of
chemical compounds. S yntax i s t he set of grammatical rules for building sentences o ut of
words. In nomenclature, syntax includes t he use of symbols, s uch as dots, commas a nd
hyphens, t he use of numbers for appropriate reasons in given places, and the order of citation
of various words, syllables and symbols.
Generally, nomenclature systems require a r oot on which to construct the name. This
root can be an element name ( e.g. ‘ cobalt’ or ‘silicon’) f or use in additive nomenclature, or
can be derived from an element name (e.g. ‘sil’ from ‘silicon’, ‘ plumb’ f rom ‘plumbum’ for
lead) and elaborated to yield a p arent hydride name ( e.g. ‘ silane’ or ‘plumbane’) f or use i n
substitutive nomenclature.
Names are constructed b y j oining other units to these roots. Among the most important
units are affixes. These are syllables added to words or roots and can be suffixes, prefixes o r
infixes a ccording to whether they are placed after, before or within a w ord or root.
Suffixes and endings are of many different kinds (Table III)*, each of which conveys
specific information. The following examples illustrate particular u ses. They may specify the
degree of unsaturation of a p arent compound in substitutive nomenclature: hexane, h exene;
and phosphane, d iphosphene, d iphosphyne. O ther endings indicate t he nature of the charge
carried by the whole compound; cobaltate refers to an anion. Further suffixes can indicate
that a n ame refers to a g roup, as in hexyl.
Prefixes i ndicate, for example, substituents in substitutive nomenclature, as in the name
chlorotrisilane, and ligands in additive nomenclature, as in the name aquacobalt.
Multiplicative prefixes (Table IV) can be used to indicate t he number of constituents or
ligands, e.g. hexaaquacobalt. Prefixes m ay also be used to describe the structural t ypes or

* T ables numbered with a R oman numeral are collected together at the end of this book.

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