Page 108 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

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

of such species are formed by an adaptation of replacement n omenclature, giving
carbaboranes, azaboranes, phosphaboranes, thiaboranes, etc.
In the heteroboranes, t he number of nearest neighbours to the heteroatom is variable
and can be 5, 6, 7, etc. Therefore, in the adaptation of replacement nomenclature to
polyborane compounds, the replacement of a b oron atom by another atom is indicated in
the name along with the number of hydrogen atoms in the resulting polyhedral s tructure.
The prefixes closo, nido, arachno, etc., a re retained as described for boron hydrides
(Section IR-6.2.3.2). The p ositions of the supplanting heteroatoms in the polyhedral
framework are indicated by locants which are the lowest possible numbers taken as a s et
consistent with the numbering of the parent polyborane. If a c hoice remains for locant
assignment within a g iven s et, then lower numbering should be assigned to the element
encountered first using Table VI.
The hydrogen atom population of the actual compound concerned (and not that of the
parent all-boron skeletal compound) is added as an arabic numeral in parentheses at the end
of the name. The numeral is retained upon hydrogen substitution.

Examples:
1. B 10 C 2 H 12 dicarba-closo-dodecaborane(12)

2. B 3 C 2 H 5
1

3 4 4
3
2 2

5

1,5-dicarba-closo-pentaborane(5)

3. B 4 C 2 H 8

1 1

2
6
5
5

3 4 4
4,5:5,6-di-mH-2,3-dicarba-nido-hexaborane(8)

Note that locants for skeletal replacement take precedence o ver those f or bridging h ydrogen
atoms. The number of bridging h ydrogen atoms is usually different for heteroboranes

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