Page 18 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-9.3 C O O R D I N A T I O N C O M P O U N D S

3. Steps
Priority 1 2 3
sequence 1
1
6 1
M .. 6
N6 .. C H 3 _ _ _ 7 1 7 1
H
0 0
1
1
6 1 6
M ..
5 _ _
N _ 7 1 7 1
H CH 3
H 1 1
1 1
1 6 1 1
4 M .. 6 1 1 1
N _ _ _
H CH 3 7 6 1 7 6 1 1
N 4 CH 3 1
1 2 1 1
N N NHMe 2 6 1 1 6
3 M 6 1 1 6 1 1
..
MeEtHN NHMe 3 M _ _ 6 1 1
N
NH Me H Et _ 7 1 7 6 1
2
5 CH 3 1 6 1 1
1 1
(6) (6.5)
M .. (6.5) 7 (6.5) 6
N 1 6 6 1 6 1
_ _ _ (6.5)
2 7 6 6
(6) 6 6 (6) 1
1 6 1 (6)
(6) 1
7
(6) (7)
M .. (6.5) 7 (7) 6 1
N 1 6 6 1 (6.5)
_ _ _ 7 6 6
1 1
N 1 6 6 7 0
(6) (6) 6
(6.5) 1
In Example 3, all the ligating atoms are nitrogen a toms. The key illustrates how proceeding
along the branches of the ligand constituents allows priorities to be assigned. T he numbers in
columns 1, 2 a nd 3 o n t he right are the atomic n umbers of the atoms in the structures, with
those in brackets b eing u sed to take account of the presence of multiple b onds. The
averaging techniques used in the case of resonance structures (last two ligands in the list) are
given in the original p aper. 13

IR-9.3.5.3 Priming convention

The priming convention i s r equired i n o rder to avoid ambiguity when using t he configuration
index to describe t he stereochemistry of systems that contain either more t han one
polydentate ligand of a p articular k ind, or a p olydentate ligand that contains m ore than one
coordinating fragment of a p articular k ind. This situation is found commonly with
bis(tridentate) complexes, but also arises in more complicated cases. The n eed for this
convention is best illustrated by example.

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