Page 30 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-2.2 G R A M M A R

(a) To enclose formulae for groups of atoms (the groups may be ions, s ubstituent g roups,
ligands or molecules), to avoid a mbiguity or when the group is being m ultiplied. In the
latter case, a m ultiplicative subscript numeral follows the closing parenthesis. In the case of
common ions such as nitrate and sulfate, parentheses are recommended but n ot mandatory.

Examples:

1. Ca 3 (PO 4 ) 2
2. [Te(N 3 ) 6 ]

3. (NO 3 ) or NO 3
4. [FeH(H 2 )(Ph 2 PCH 2 CH 2 PPh 2 ) 2 ] þ

5. PH(O)(OH) 2
6. [Co(NH 3 ) 5 (ONO)][PF 6 ] 2

(b) To enclose the abbreviation of a l igand name i n f ormulae. (Recommended ligand
abbreviations are given i n T ables V II and VIII. See also S ections IR-4.4.4 and IR-9.2.3.4.)

Example:
7. [Co(en) 3 ] 3þ

(c) To enclose the superscripted radical dot and its multiplier f or polyradicals, in order to
avoid ambiguity in relation to multiplying t he charge symbol.

Example:
8. NO (2 *)

(d) In solid-state chemistry, to enclose symbols of atoms occupying the same type of site in
a r andom f ashion. The symbols themselves are separated by a c omma, w ith no space.

Example:

9. K(Br,Cl)

(e) In solid-state chemistry, to indicate an atom or a g roup of atoms in a t etrahedral site.

Example:

10. (Mg)[Cr 2 ]O 4

(f) To indicate t he composition of a n on-stoichiometric compound.

Examples:
11. Fe 3x Li 4-x Ti 2(1-x) O 6 (x ¼ 0.35)
12. LaNi 5 H x (05x566.7)

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