Page 89 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)
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C O M  P O S I T I O N A L  N  O M  E N C L A T U R E               I  R-5.5





                       Examples:
                           7. K 2 O        d  ipotassium oxide
                                           dipotassium (dioxide), or potassium dioxide(2 )
                           8. K 2 O 2
                                           monopotassium (dioxide), or potassium dioxide(1 )
                           9. KO 2
                          10. KO 3         potassium (trioxide), or potassium trioxide(1 )

                       Clearly, a  simple  s toichiometric name  l ike ‘potassium dioxide’, although strictly speaking
                       unambiguous (referring to the compound in Example 9), could  e asily be misinterpreted. I n
                       other cases, based on chemical knowledge, there is no chance  o  f  m  isinterpretation in
                       practice, and the simple stoichiometric name  w  ill  m  ost  o ften be used, as in Examples 11
                       and 12 below.

                       Examples:
                                           barium dioxide (simple stoichiometric name), or barium (dioxide)
                          11. BaO 2
                                           or barium dioxide(2 ) ( specifying the diatomic anion), or barium
                                           peroxide (using the acceptable alternative name for the anion)
                                           manganese dioxide (simple stoichiometric name), or manganese
                          12. MnO 2
                                           bis(oxide) (specifies two oxide ions rather than a  d iatomic anion),
                                           or manganese(IV) oxide



           IR-5.5      N A M  E S  O  F  ( F O R M  A L )  A  D D I T I O N  C  O M  P O U N D S

                       The term addition compounds covers  d onor-acceptor complexes (adducts) and a  v ariety  o f
                       lattice compounds. The  m  ethod described here,  h  owever, is relevant  n  ot just to such
                       compounds, but also to multiple  s alts and to certain compounds of uncertain structure or
                       compounds for which the full structure need not be communicated.
                          The names of the individual components  o f  s uch a  g eneralized addition compound are
                       each constructed by using an appropriate nomenclature system,  w  hether  c ompositional,
                       substitutive or additive. The overall name of the compound is then formed by connecting the
                       names of the components  b y  ‘ em’ dashes; the proportions of the components are indicated
                       after the name  b y  a  stoichiometric descriptor consisting of arabic numerals separated by a
                       solidus or solidi. T he descriptor, in parentheses, is separated from the compound name  b y  a
                       space. The order of names of the individual components is, firstly, according to the
                       increasing number of the components  a nd, secondly, alphabetical.  A  s  t he only exception,
                       the component name ‘water’ is always cited last. (Note that this represents a c hange from the
                       rule in Ref. 2  a ccording to which the component names must follow the order given by
                       the formula.) The numerals in the descriptor appear in the same  o rder as the corresponding
                       component names.
                          For addition compounds containing water as a  c omponent, the class name  ‘ hydrates’ is
                       acceptable because of well established use, even though  t he ending ‘ate’ might seem to
                       indicate an anionic component.  F or hydrates with a  s imple stoichiometry, names of the
                       classical ‘hydrate’ type are acceptable, but rules have not been formulated for non-integer
                       stoichiometries such as that in Example 12 below. Also, because of their ambiguity, the


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