Page 86 - 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

Examples:
calcium bis(trioxidonitrate), or calcium nitrate
5. Ca(NO 3 ) 2
bis(dioxidouranium) tetraoxidosulfate
6. (UO 2 ) 2 SO 4
barium bis(tetrafluoridobromate)
7. Ba(BrF 4 ) 2
8. U(S 2 O 7 ) 2 uranium bis(disulfate)
tricalcium bis(phosphate)
9. Ca 3 (PO 4 ) 2
calcium diphosphate
10. Ca 2 P 2 O 7
calcium bis(hydrogencarbonate)
11. Ca(HCO 3 ) 2

IR-5.4.2.2 Use of charge and oxidation numbers
It is possible t o p rovide information on the proportions of the constituents in names by using
one of two other d evices: the charge number, which designates ionic charge, and the
oxidation number, which designates oxidation s tate. In nomenclature, the use of the charge
number is preferred as the determination of the oxidation n umber is sometimes ambiguous
and subjective. It is advisable to use oxidation numbers only when t here is no uncertainty
about their assignment.
The charge number is a n umber whose m agnitude is the ionic charge. It is written i n
parentheses immediately after the name of an ion, without a s pace. The c harge is written i n
arabic numerals, followed by the sign of the charge. Note that unity is always indicated,
unlike in superscript charge designations (which a re used in formulae). No charge number is
used after the name o f a neutral species.

Examples:

1. FeSO 4 iron(2þ) s ulfate
iron(3þ) s ulfate
2. Fe 2 (SO 4 ) 3
dioxidouranium(1þ) s ulfate
3. (UO 2 ) 2 SO 4
dioxidouranium(2þ) s ulfate
4. UO 2 SO 4
5. K 4 [Fe(CN) 6 ] p otassium hexacyanidoferrate(4 )
6. [Co(NH 3 ) 6 ]Cl(SO 4 ) h exaamminecobalt(3þ) c hloride sulfate

The oxidation number (see Sections IR-4.6.1 and IR-9.1.2.8) of an element is indicated by
a R oman numeral placed in parentheses immediately following the name (modified b y
the ending ‘ate’ if necessary) of the element to which it refers. The oxidation number
may be positive, negative o r z ero (represented by the numeral 0). An oxidation number is
always non-negative unless the minus sign is explicitly used (the positive sign is never
used). Non-integral oxidation numbers are not used for nomenclature purposes.

Examples:
7. PCl 5 phosphorus(V) chloride
8. Na[Mn(CO) 5 ] s odium pentacarbonylmanganate( I)
9. [Fe(CO) 5 ] p entacarbonyliron(0)

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