Transition metal azide complex
Transition metal azide complexes are coordination complexes containing one or more azide (N3−) ligands.[2]
Structure and bonding
Azide is a
Homoleptic complexes
![](http://upload.wikimedia.org/wikipedia/commons/thumb/9/95/CSD_CIF_RIJLAX.png/220px-CSD_CIF_RIJLAX.png)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/27/Nb%28N3%297.png/220px-Nb%28N3%297.png)
Many homoleptic complexes (with only one kind of ligand) are known. Coordination numbers range from 2 (e.g., [Au(N3)2]−) to 7 (e.g., [W(N3)7]−). Many homoleptic complexes are octahedral anions of the type [M(N3)6]n-:
- dianions for tetravalent metals V, Pt, Ti, Zr, Hf
- trianions for trivalent metals Cr, Fe, Ru, Rh, Ir
- tetraanions for the divalent Ni
For some metals, homoleptic complexes exist in two oxidation states: [Au(N3)2]− vs [Au(N3)4]− and [Pt(N3)6]4- vs [Pt(N3)4]2-.[2]
Mixed ligand complexes
Azide forms myriad mixed ligand complexes. Examples include Zn(N3)2(NH3)2 and (C5H5)2Ti(N3)2.
Synthesis and reactions
Traditionally, metal azide complexes are prepared by
Heating and, in some cases, UV radiation often cause azide complexes to release nitrogen gas. This behavior is the basis of their frequent explosive properties (see
Azide ligands are react with nitrosonium to give nitrous oxide. This reaction is used to generate coordinatively unsaturated complexes.[6]
- [Co(NH3)5N3]2+ + NO+ + H2O → [Co(NH3)5(H2O)]3+ + N2O + N2
Metal complexes of organic azides are intermediates in the azide-alkyne Huisgen cycloaddition, the basis of Click chemistry.