Page 105 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

S U B S T I T U T I V E N O M E N C L A T U R E IR-6.2

endings. The endings are given in Table IR-6.3. (Hydrides with intermediate degrees of
hydrogenation are named by the use of the prefix ‘hydro’ together with an appropriate
multiplicative prefix. However, such hydrides are not parents.)
The order of citation of the heteroatoms follows Table VI, i.e. F4Cl4Br4
I4O4. . . etc., where ‘4’ m eans ‘is cited before’. L ocants a re assigned to the hetero-
atoms so as to ensure fi rst that the locant ‘1’ is given to the atom cited first and then that
the total set of locants is as low as possible c onsistent with sequential numbering of the
ring positions (ordering locant sets a lphanumerically). The heteroatoms are cited by the
replacement prefixes (‘a’ t erms) given i n T able X t ogether with appropriate multipli-
cative prefixes. (As e xceptions, the ‘a’ terms for aluminium and indium in the Hantzsch–
Widman s ystem are ‘aluma’ and ‘indiga’.) In the case of six-membered rings, the ring
heteroatom which is cited last d ecides which of the alternative endings in Table IR-6.3 is
chosen.
Tautomers may be distinguished using indicated hydrogen to specify the location
of the hydrogen atom(s) which can be placed in more t han one way [and thus,
indirectly, the location of the double b ond(s)], as in Example 2 b elow.

Table IR-6.3 Endings in the Hantzsch–Widman system

Number of Mancude a Saturated
atoms in ring

3 i rene (‘irine’ for rings irane (‘iridine’ for rings containing N)
with N a s o nly heteroatom)
4 e te etane (‘etidine’ for rings containing N)
5 o le olane (‘olidine’ for rings containing N)
6(A) b ine ane
6(B) b ine inane
6(C) b inine inane
7 e pine epane
8 o cine ocane
9 o nine onane
10 ecine ecane

a
Maximum number of non-cumulative double bonds.
b
6(A) is used when the last-cited heteroatom is O, S, Se, Te, Po or Bi; 6(B) is used when the last-cited
heteroatom is N, Si, Ge, Sn or Pb; and 6(C) is used when the last-cited heteroatom is F, Cl, Br, I, P, As,
Sb, B, Al, Ga, In or Tl.

(ii) Alternatively, the name i s b ased on the name of the corresponding carbocycle, and the
heteroatoms are indicated by the replacement prefixes ( ‘a’ terms) f rom Table X t ogether
with appropriate multiplicative prefixes. The order of citation i s a gain given by Table VI.
(iii) For the special case of saturated rings of two alternating skeletal atoms (as in
Examples 3 –6 below), the name m ay be constructed using the prefix ‘cyclo’ followed
by the replacement prefixes (Table X) cited in the reverse of the order in which the
corresponding elements appear in Table VI. The name e nds with ‘ane’.

The Hantzsch–Widman names are preferred for rings with up to 10 members, in organic
nomenclature. For saturated rings and mancude rings (rings with the maximum number of

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