Mononuclear compounds nomenclature

In compositional nomenclature, ligands are given in alphabetical order before central atoms. Central atoms are listed in alphabetical order as well. Bridging ligands to the extent known are indicated by the p notation (see Section 3.2.3.4). The numbers of ligands and central atoms are indicated by the appropriate numerical prefixes (see Section 3.3.2). Anions, cations, oxidation states and ionic charges are indicated in the same manner as in mononuclear compounds (see Section 3.3.3). For examples see Table 14. 

The designation of central atom and ligands, generally straightforward in mononuclear complexes, is more difficult in polynuclear compounds where there are several central atoms in the compound to be named, e.g. in polynuclear coordination compounds, and chain and ring compounds. In each case, a priority order or hierarchy has to be established. A hierarchy of functional groups is an established feature of substitutive nomenclature Table VI shows an element sequence used in compositional and additive nomenclature. 

In the stereochemical nomenclature of coordination compounds, the procedure for assigning priority numbers to the ligating atoms of a mononuclear coordination system is based upon the standard sequence rules developed for chiral carbon compounds (the Cahn, Ingold, Prelog or CIP rules6, see Section IR-9.3.3.2). 

---