Formulae multiplicative prefixes

The simplest type of compositional name is a stoichiometric name, which is just a reflection of the empirical formula (Section IR-4.2.1) or the molecular formula (Section IR-4.2.2) of the compound. In stoichiometric names, proportions of constituent elements may be indicated in several ways, using multiplicative prefixes, oxidation numbers or charge numbers. 

Ligands in polynuclear complexes are cited in alphabetical order both in formulae and names. The number of each ligand is specified by subscript numerical multipliers in formulae (Sections IR-9.2.3.1 to IR-9.2.3.4) and by appropriate multiplicative prefixes in names (Sections IR-9.2.2.1 to IR-9.2.2.3). The number of central atoms of a given kind, if greater than one, is indicated similarly. 

The prefix trans tells us that the triphenylphosphine groups occupy opposite corners of a square rather than adjacent corners (cis). The use of chloro in the name (instead of chloride ) implies the absence of discrete chloride ions, as in [Ir(CO)(PPh3)2]+Cr. Names, as opposed to formulae, are easier to index or to store in a data bank for the rapid retrieval of information on compounds having specific structural features. If a chemist wished to collect the available thermodynamic data for inorganic nitrites, a computer search of formulae containing NOz or some multiple thereof would produce a vast number of organic nitro-compounds of no... 

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