Page 103 - 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

This method of locating b ridging h ydrogen atoms is adapted from the ‘indicated
hydrogen’ method in organic nomenclature (see Section P-14.6 of Ref. 1). The ‘indicated
hydrogen’ method would y ield the name (2,3-mH),(2,5-mH),(3,4-mH),(4,5-mH)-nido-
pentaborane(9).

IR-6.2.4 Heteronuclear parent hydrides

IR-6.2.4.1 Heteronuclear acyclic parent hydrides in general

When at least four carbon atoms in an unbranched-chain parent hydrocarbon are replaced by
heteroatoms, alike or different, a nd the terminal carbon atoms either remain o r a re replaced
by P, As, Sb, Bi, Si, Ge, Sn, Pb, B, Al, Ga, In, or Tl, skeletal replacement nomenclature (‘a’
nomenclature) may be used to indicate t he heteroatoms (see Sections P-15.4 and P-21.2 of
Ref. 1).
In this method, the chain is named first as if it were composed entirely of carbon atoms.
Any heteroatoms in the chain are then designated by appropriate replacement prefixes (‘a’
terms) from Table X c ited in the order given b y T able VI, each preceded by its appropriate
locant. The locants are assigned by numbering the chain from that end which gives l ower
locants to the heteroatom set as a w hole and, if these are equal, from that end which gives
the lower locant or locant set to the replacement prefix first cited. If there is still a c hoice,
lower locants are assigned to the sites of unsaturation.
Only chains with four or more heteroatoms (or strictly speaking, four or more
heterounits) are given p arent names constructed in this way. A heterounit is a s equence of
heteroatoms which is in itself t he skeleton of a p arent hydride, e.g. S e a nd SS and SiOSi
(see Section IR-6.2.4.2), but not OSiO. Heteroatoms must n ot belong to the principal
characteristic group (see Section IR-6.3.1) (if there i s o ne) when c ounting them for this
purpose. Heteronuclear chains with fewer heterounits, and heteronuclear c hains not
terminating in any of the atoms listed a bove, are named substitutively as derivatives of
homonuclear parent hydrides and are not themselves used as parents.

Examples:
1. H
N
H N NH 2
2
N-(2-aminoethyl)ethane-1,2-diamine

2. H
N NH 2
H N N
2
H
0
N,N -bis(2-aminoethyl)ethane-1,2-diamine
3.
11 10 9 8 7 6 5 4 3 2 1
CH 3 O CH 2 CH 2 OCH 2 CH 2 SiH 2 CH 2 SCH 3
7,10-dioxa-2-thia-4-silaundecane

(Parent name. Note t he name is not 2,5-dioxa-10-thia-8-silaundecane because the
locant set 2,4,7,10 takes precedence o ver the locant set 2,5,8,10.)

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