Page 84 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-5.4 C O M P O S I T I O N A L N O M E N C L A T U R E

Note that in Ref. 1, radical anions consisting of only hydrogen and one other element
were named additively using the ending ‘ide’ rather than the ending ‘ ate’ (e.g. Example 5
above). Making this exception to the general system of additive nomenclature for these
particular c ases i s n ow discouraged.
When one or more hydron(s) are attached to an anion a t ( an) unknown p osition(s), or at
(a) position(s) w hich one cannot or does not wish to specify, a ‘hydrogen name’ (see Section
IR-8.4) m ay be used. Such names may also b e u sed for simpler compounds, such as partially
dehydronated oxoacids. Certain of these n ames have accepted a bbreviated forms, such as
hydrogencarbonate, dihydrogenphosphate, etc. A ll such accepted a bbreviated names are
given in Section IR-8.5.

Examples:

12. HMo 6 O 19 hydrogen(nonadecaoxidohexamolybdate)(1 )

13. HCO 3 hydrogen(trioxidocarbonate)(1 ), or hydrogencarbonate

14. H 2 PO 4 dihydrogen(tetraoxidophosphate)(1 ),
or dihydrogenphosphate

IR-5.4 G E N E R A L I Z E D S T O I C H I O M E T R I C N A M E S

IR-5.4.1 Order of citation of electropositive and electronegative constituents

The constituents of the compound to be named are divided into formally e lectropositive and
formally e lectronegative constituents. There must be at least one electropositive and one
electronegative constituent. Cations are electropositive and anions electronegative, by
definition. Electropositive elements occur later in Table VI than electronegative elements by
convention.
In principle, the division into electropositive and electronegative constituents is arbitrary
if the compound contains more than two elements. In practice, however, there is often no
problem in deciding where the division lies.
The names of the electropositive constituents precede those o f t he electronegative
constituents in the overall name. The order of citation is alphabetical within each class of
constituents (multiplicative p refixes b eing ignored), e xcept t hat hydrogen is always cited last
among electropositive constituents if actually classified as an electropositive constituent.
This principle for constructing generalized stoichiometric names parallels t he principle for
constructing ‘generalized salt formulae’ in Section IR-4.4.3.4. However, the order of citation
in a g eneralized stochiometric name i s n ot necessarily the same as the order of symbols in the
corresponding generalized s alt formula, as is seen from Examples 4, 5 a nd 7 b elow.
The following generalized stoichiometric names, based only on single-element
constituents, do not carry information about the structure.

Examples:

1. IBr iodine bromide
2. PBrClI phosphorus bromide chloride iodide
3. ArHF or ArFH argon hydrogen fluoride, or argon fluoride hydride

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