Page 20 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-1.6 G E N E R A L A I M S , F U N C T I O N S A N D M E T H O D S

the rule s tated above, these are now fluorido, chlorido, bromido, iodido, hydroxido, hydrido,
cyanido, oxido, etc. I n p articular, thio is now reserved f or functional replacement
nomenclature (see Section IR-8.6), and the ligand S 2 is named sulfido.
In a n umber of cases the names of (formally) anionic ligands have changed a s a result of
modifications to the nomenclature of the anions themselves (see Section IR-1.6.2). For
example, the ligand HNNH is now named hydrazine-1,2-diido (Example 3 in Section

IR-1.6.2), and HNCO * was (hydridonitrido)oxidocarbonate( * 1 ) i n R ef. 22 but is now
named (hydridonitrato)oxidocarbonate( * 1 ).
Particular attention has been given to providing the correct names and endings for
organic ligands. T hus, with reference to Examples 4 a nd 5 i n S ection IR-1.6.2,
methanaminido is now used rather than methaminato, and a p orphyrin ligand is named
porphyrin-21,23-diido rather than the name porphyrinato(2 ) ( which is used in Ref. 11).
The systematic organic ligand names given i n T able VII are now in accord with anion
names derived by the rules of Ref. 21. In a n umber of cases t hey differ from the names given
as systematic in Ref. 11.

IR-1.6.5 Formulae for (formal) c oordination entities
In the formulae for coordination entities, ligands are now ordered alphabetically according
to the abbreviation or formula used for the ligand, irrespective of charge (Sections IR-4.4.3.2
and IR-9.2.3.1).
In Ref. 11, c harged ligands were cited before neutral ligands. Thus, two ordering
principles were in use for no obvious reason other than tradition, and the person devising t he
formula needed t o d ecide whether a p articular l igand was charged. Such a d ecision is not
always straightforward.
2
Thus, for example, the recommended f ormula f or the anion of Zeise’s salt is now [Pt(Z -
2

C 2 H 4 )Cl 3 ] whereas in Ref. 11 it was [PtCl 3 (Z -C 2 H 4 )] because chloride is anionic.
IR-1.6.6 Additive names of polynuclear entities
The system developed in Ref. 11 for additive names of dinuclear and polynuclear entities
has been clarified and to some e xtent changed for reasons of consistency: the order of
citation o f c entral atoms in names is now always the order in which they appear in Table VI,
the element occurring later being cited first (see Sections IR-7.3.2 a nd IR-9.2.5.6).
The system can be used for polynuclear entities with any central atoms. In this s ystem,
the order of the central atoms in the name r eflects the order in which they are assigned
locants to be used in the kappa convention ( Section IR-9.2.4.2) for specifying which ligator
atoms coordinate to which central atoms. The atom symbols used at the end of the name t o
indicate metal-metal bonding are similarly ordered. Thus, for example, [(CO) 5 ReCo(CO) 4 ]
5
4
is now named nonacarbonyl-1k C,2k C-rheniumcobalt(Re—Co) r ather than nonacarbonyl-
5
4
1k C,2k C-cobaltrhenium(Co—Re) ( as in Ref. 11).
IR-1.6.7 Names of inorganic acids
The names of inorganic acids are dealt with separately in Chapter I R-8.

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