There are a variety of ligands where the coordination to the metal ion is through a non-bonding electron pair at nitrogen. Ammonia is one example of this type of ligand.
Other examples where coordination is through a non-bonding electron pair at nitrogen are shown below:
CN– (cyanide ion, named as cyano - may also be cyanido)
SCN– (thiocyanate ion, name as thiocyanto)
H2NCH2CH2NH2 (ethane-1,2-diamine, often abbreviated as en)
For complexes having ligands with more complicated names (such as thiocyanato and ethane-1,2-diamine)
bis and
tris are used instead of
di and
tri to indicate the number of these ligands that are present. An example showing the name and formula for such a complex is given below.
dichlorobis(ethane-1,2-diamine)platinum(IV) chloride
[PtCl2(en)2]Cl2
Note that when
bis and
tris are used,
the name of the ligand is enclosed in brackets.
Ethane-1,2-diamine is a bidentate ligand.
Another common example of a bidentate ligand is oxalate anion (
–O
2C–CO
2–).
This anion is named as oxalato and often abbreviated as ox in formulae for coordination compounds.
The tris(oxalato)ferrate(III) ion has the formula [Fe(ox)3]3–