Page 166 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-9.2 C O O R D I N A T I O N C O M P O U N D S

Example 2 i llustrates how coordination by the two terminal primary amino groups of the
ligand is indicated by placing the kappa index a fter the substituent g roup name a nd within
the effect of the ‘bis’ doubling prefix. The appearance of the simple i ndex kN after the
‘ethane-1,2-diamine’ indicates the binding by only one of the two equivalent secondary
amino nitrogen atoms.
Only one of the primary amines is coordinated in Example 3. This is indicated by not
using the doubling prefix ‘bis’, repeating (2-aminoethyl), and inserting the k index o nly in
the first such unit, i.e. (2-amino-kN-ethyl). The involvement o f b oth of the secondary ethane-
2
0
1,2-diamine nitrogen atoms in chelation is indicated by the index k N,N .
Tridentate chelation by the tetrafunctional macrocycle in Example 4 i s s hown b y t he
kappa index f ollowing the ligand name. The ligand locants are required i n o rder to
distinguish this complex f rom those where the central atom is bound to other combinations
of the four potential donor atoms.

Example:
4.

S S
MoCl 3
S S

3 1,4,8
trichlorido(1,4,8,12-tetrathiacyclopentadecane-k S )molybdenum, o r
8
3 1
4
trichlorido(1,4,8,12-tetrathiacyclopentadecane-k S ,S ,S )molybdenum
Well-established modes o f c helation of the (ethane-1,2-diyldinitrilo)tetraacetato ligand
(edta), n amely bidentate, tetradentate and pentadentate, are illustrated in Examples 5–8. The
multiplicative prefix ‘tetra’ used in Example 5 c annot be used in Examples 6 a nd 7 b ecause
of the need to avoid a mbiguity a bout which acetate a rms are coordinated to the central atom.
In such cases the coordinated fragments are cited before the uncoordinated fragments in the
ligand name. Alternatively, a modified name may be used, as in Example 7, where the use of
the preferred IUPAC name N,N -ethane-1,2-diylbis[N-(carboxymethyl)glycine] (see Section
0
P-44.4 of Ref. 1) is demonstrated.

Examples:
5. 4 −
H C 2 C H 2
(O CCH ) N N(CH CO )
2
2 2
2
2 2
Pt II
Cl Cl
2
dichlorido[(ethane-1,2-diyldinitrilo-k N,N )tetraacetato]platinate(4 )
0
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