Page 73 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)
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F O R M  U L A E                                                    IR-4.5





           IR-4.5      I S O T O P I C A L L Y  M  O D I F I E D  C O M  P O U N D S

           IR-4.5.1    General formalism
                       The mass number of any specific nuclide can be indicated in the usual way with a  l eft
                       superscript preceding the appropriate atomic symbol (see Section IR-3.2).
                          When it is necessary to cite different nuclides at the same position in a  f ormula, the
                       nuclide symbols are written  i n  a  lphabetical order; when their atomic  s  ymbols are
                       identical the order is that of increasing mass number. Isotopically modified compounds
                       may be classified as isotopically substituted compounds  a  nd isotopically labelled
                       compounds.


           IR-4.5.2    Isotopically substituted compounds
                       An isotopically substituted compound has a  c omposition such that all the molecules of the
                       compound have only the indicated nuclide(s) at each designated position. The  s ubstituted
                       nuclides  a re indicated by insertion of the mass  n umbers as left superscripts  p receding the
                       appropriate atom symbols in the normal formula.

                       Examples:

                                3
                           1. H HO
                                36
                           2. H Cl
                           3.  235 UF 6
                                   14
                           4.  42 KNa CO 3
                           5.  32 PCl 3
                                32
                           6. K[ PF 6 ]
                                42
                                       14
                           7. K 3 K[Fe( CN) 6 ]

           IR-4.5.3    Isotopically labelled compounds

           IR-4.5.3.1  Types of labelling

                       An isotopically labelled compound may be considered formally  a  s  a  mixture of an
                       isotopically unmodified compound and one or more analogous isotopically substituted
                       compounds. They may be divided into several different types. Specifically labelled
                       compounds and selectively labelled compounds are treated briefly here and described in
                       more detail in Ref. 5.

           IR-4.5.3.2  Specifically labelled compounds

                       An isotopically labelled compound is called a  s pecifically labelled compound when a
                       unique  i  sotopically  s  ubstituted compound is added formally to the analogous
                       isotopically unmodified  c  ompound. A  s pecifically labelled compound is indicated by
                       enclosing the appropriate nuclide symbol(s) and multiplying subscript (if any) in square
                       brackets.


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