Page 128 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-7.4 A D D I T I V E N O M E N C L A T U R E

2.

dicycle

3.

tricatenadicycle

IR-7.4.2 Nodal descriptor

The connectivity in the molecular framework i s i ndicated by a nodal descriptor, w hich
is placed in square brackets i mmediately before the terms ‘catena’, ‘cycle’ or ‘catenacycle’.
The atoms are numbered according to the general nodal nomenclature regardless of their
identity. Only in the case of ambiguity a re the identities of the atoms taken into consideration.
The first part of the descriptor indicates the number of atoms in the main chain. The
arabic numerals after the full stop indicate the lengths of the branches cited in priority order.
A s uperscript locant for each branch d enotes the atom in the part of the molecule already
numbered to which the branch i s a ttached.
A z ero in the descriptor indicates a r ing and is followed by an arabic numeral indicating
the number of atoms in the main ring. For polycyclic systems, the numbering begins from
one of the bridgeheads and proceeds in the direction which gives t he lowest possible l ocant
for the other bridgehead. In this case, t he number of atoms in the bridge is cited after the full
stop. A p air of superscript locants is inserted for each such bridge numeral, s eparated by a
comma and cited in increasing numerical order.
An assembly d escriptor consists of square brackets e nclosing, in the order of their
seniority (see Ref. 2 f or rules), t he nodal descriptors of each module in parentheses. Between
the descriptors of the modules, the locants of the nodes linking t he modules are indicated.
These locants, s eparated by a c olon, are the atom numbers in the final numbering of the
entire assembly ( compare E xample 7 b elow with Examples 5 a nd 6).

Examples:
1. 1 7

descriptor: [7]

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