Azides of Cadmium

The normal cadmium azide, Cd(N3)2, is a white, crystalline solid which is hygroscopic and tends to hydrolyze. Thus, the salt turns yellow when exposed to atmospheric moisture. The azide dissolves in water, probably as an aquo complex. Upon standing, the solution turns yellow and slowly precipitates basic products [62,215,216]. Excess azide ion in the solution leads to the formation of various azido complexes with a maximal ligand number of 5 [217,218] excess pyridine forms a diazidodipyridine complex [62,188,219,220]. 

Cadmium azide is made in aqueous media, usually by dissolving the carbonate or hydroxide in hydrazoic acid [62,73,115,157,215]. The product is crystallized from the yellow, filtered solution by evaporating or cooling to yield slightly yellow crystal needles of 98.5% purity. A white product of higher purity (99.5%) is obtained by keeping the reaction mixture acidified with strong hydra-zoic acid [215]. 

Curtius and Rissom [62] reacted cadmium azide with pyridine to obtain a colorless complex containing two azide and two pyridine ligands. Stoichiometric amounts of pyridine and sodium azide are mixed with 0.5 M cadmium nitrate  

Another complex, which was isolated as the tetraphenylphosphonium salt [139,173, 222], has the possible binuclear structure [Cd2(N3)s] . 

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