Page 53 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

G R A M M A R I R-2.16

Example:
1. [Cr 2 (m-O)(OH) 8 (m-OH)] 5
m-hydroxido-octahydroxido-m-oxido-dichromate(5 )

Thus, for both formulae and names the terminal ligands are closer to the central atom, with
the multiplicity of the bridging l igands increasing further away from the metal.

IR-2.15.3.5 Ordering components in salt formulae and names

In formulae and names of salts, double salts and coordination compounds, cations precede
anions. Ordering within each of these groups is alphabetical, cf. S ection IR-2.15.2.

IR-2.15.3.6 Isotopic m odification
In isotopically modified compounds, a p rinciple governs the order of citation o f n uclide
symbols. ( See Section II-2.2.5 of Ref. 2.)

IR-2.15.3.7 Stereochemical priorities

In the stereochemical nomenclature of coordination compounds, the procedure for assigning
priority numbers to the ligating atoms of a m ononuclear coordination system is based upon
the standard s equence rules developed for chiral carbon compounds (the Cahn, Ingold,
6
Prelog or CIP rules , s ee Section IR-9.3.3.2).
IR-2.15.3.8 Hierarchial ordering of punctuation marks

In the names of coordination compounds and boron compounds, t he punctuation marks used
to separate the symbols of atoms from the numerical locants, the locants indicating bridging
atoms, and the various other sets of locants which may be present, a re arranged in the
following hierarchy:

semicolon 4 colon 4 comma:

The colon is only used for bridging l igands, s o t hat the more r estricted general hierarchy is
simply comma 5 semicolon. The s equence when b ridging ligands are being specified is
comma 5 colon. (See Example 2 i n S ection IR-2.5.2, and Section IR-9.2.5.5.)

IR-2.16 F I N A L R E M A R K S

In this chapter, the various uses of letters, numerals and symbols in names and formulae
have been gathered under common headings to provide an easy check to ensure that the
constructed name o r f ormula is in accord with agreed practice. However, this chapter is
not sufficient to make clear all the rules needed t o b uild a n ame o r a formula, and the
reader is therefore advised to consult other a ppropriate chapters for the more d etailed
treatment.

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