Page 173 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

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

bridging i s l isted i n d escending o rder of complexity, e.g. m 3 -oxido-di-m-oxido-trioxido. For
ligand names requiring enclosing marks, m is contained within those marks.
The kappa convention is used together with m when it is necessary t o s pecify which
central atoms are bridged, and through which donor atoms. The k appa descriptor counts all
3
donor atom-to-central atom bonds so that in Example 2 b elow the descriptor 1:2:3k S
specifies all three bonds from the sulfur atom bridging c entral atoms 1, 2 a nd 3.

Example:

2.
S FeSPh 2−
PhSFe S
PhSMo S
S MoSPh

[Mo 2 Fe 2 S 4 (SPh) 4 ] 2
tetrakis(benzenethiolato)-1kS,2kS,3kS,4kS-tetra-m 3 -sulfido-
3
3
3
3
1:2:3k S;1:2:4k S;1:3:4k S;2:3:4k S-(dimolybdenumdiiron)ate(2 )
Here, the two molybdenum atoms are numbered 1 a nd 2 a nd the two iron atoms 3 a nd 4
according to the rule in Section IR-9.2.5.1. Due to the symmetry of the compound, it is not
necessary t o d istinguish between 1 and 2 o r b etween 3 a nd 4.

Example:

0
3. [O 3 S(m-O 2 )SO 3 ] 2 m-peroxido-1kO,2kO -hexaoxidodisulfate(2 )
When single ligating atoms bind to two or more c entral atoms, the central atom locants are
2
2
2
separated by a c olon. For e xample, tri-m-chlorido-1:2k Cl;1:3k Cl;2:3k Cl- indicates that
there are three bridging c hloride ligands and they bridge between central atoms 1 a nd 2, 1
and 3, and 2 a nd 3. Note that because of the use of the colon, sets of bridge locants are
separated here by semicolons rather than commas.
Example:

4. H 6+
O
Co Co(NH ) 4
3
O
H 3

[Co{(m-OH) 2 Co(NH 3 ) 4 } 3 ] 6þ
4
4
4
dodecaammine-1k N,2k N,3k N-hexa-m-hydroxido-
4
4
4
1:4k O;2:4k O;3:4k O-tetracobalt(6þ)
The central atom locants given in this example a re assigned by following the rules in
Sections IR-9.2.5.5 and IR-9.2.5.6. In this case, the central cobalt atom is assigned the
locant 4.

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