Page 142 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-8.3 I N O R G A N I C A C I D S A N D D E R I V A T I V E S

IR-8.3 A D D I T I V E N A M E S

Molecules or ions that can formally be regarded as mononuclear coordination entities may
be named additively, applying the rules described in Chapter IR-7.

Examples:

þ
1. H 3 SO 4 ¼ [SO(OH) 3 ] þ trihydroxidooxidosulfur(1þ)
2. H 2 SO 4 ¼ [SO 2 (OH) 2 ] d ihydroxidodioxidosulfur

3. HSO 4 ¼ [SO 3 (OH)] hydroxidotrioxidosulfate(1 )
Structures which can be regarded as oligonuclear coordination entities may be named as
such (Section IR-7.3) o r m ay be named using t he system for inorganic c hains and rings
(Section IR-7.4).
In principle, the choice of method in the latter case is arbitrary. However, the machinery
of coordination compound nomenclature was developed to enable t he handling of complex
structures i nvolving polyatomic, and particularly polydentate, ligands and sometimes
multiply b ridging ligands. F urthermore, the separation into l igands and central atoms,
obvious in compounds most usually classified as coordination compounds, m ay be less
obvious in the polyoxoacids. Thus, additive nomenclature of the coordination type tends to
be more intricate than necessary when naming polyoxoacids forming relatively simple
chains and rings. Here the chains and rings system is easily applied, a nd the names so derived
are easy to decipher. However, this system can lead t o l ong names with many locants.
Both types o f a dditive names are exemplified below f or oligonuclear systems.

Examples:
4. The compound commonly named diphosphoric acid, H 4 P 2 O 7 ¼
[(HO) 2 P(O)OP(O)(OH) 2 ], is named according to the coordination-type additive
nomenclature as:
m-oxido-bis[dihydroxidooxidophosphorus]
or as a fi ve-membered chain with ligands:
1,5-dihydrido-2,4-dihydroxido-2,4-dioxido-1,3,5-trioxy-2,4-diphosphy-[5]catena

5. The compound commonly named cyclo-triphosphoric acid:
O OH
O
P P
HO O
O O
P
O OH
H P O 9
3 3
may be named according to coordination-type additive nomenclature as:
tri-m-oxido-tris(hydroxidooxidophosphorus),
or as a s ix-membered ring with ligands:
2,4,6-trihydroxido-2,4,6-trioxido-1,3,5-trioxy-2,4,6-triphosphy-[6]cycle

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