Cadmium complexes azides

Narang, K. K. et al., Synth. React, lnorg. Met.-Org. Chem., 1996, 26(4), 573 The explosive properties of a series of 5 amminecobalt(III) azides were examined in detail. Compounds were hexaamminecobalt triazide, pentaammineazidocobalt diazide, cis- and fram-tetraamminediazidocobalt azide, triamminecobalt triazide [1], A variety of hydrazine complexed azides and chloroazides of divalent metals have been prepared. Those of iron, manganese and copper could not be isolated cobalt, nickel, cadmium and zinc gave products stable at room temperature but more or less explosive on heating [2],... 

While the environmental impact of cadmium azide in deep oil deposits is relatively low, the long-term use of Pb(N3)2 and lead styphnate in military training grounds has resulted in considerable lead contamination (see Ch. 1.2.3, see Fig. 1.17). On demand lead azide (ODLA) is available from the reaction of lead acetate and sodium azide. The recently introduced iron and copper complexes of the type [Cat]2 [Mn(NT)4(H20)2] ([Cat]+ = NH4, Na+ M = Fe, Cu NT = 5-nitrotetra-zolate) as green primary explosives [3] are relatively easily obtained and show similar initiator properties as those of lead azide (Tab. 2.2). 

In salts of [Zn(NCS)4], the thiocyanate ligand is N-bonded, whereas it is S-bonded to cadmium in [Cd(SCN)4] salts, reflecting the respective hard and soft characters of the respective metal ions. Zinc complexes with the azide ion are well known crystallographic determinations of the structures of the compounds M2Zn(N3)4 (M = K or Cs) show the presence of discrete [Zn(N3)4] tetrahedra with linear azide groups. Some of the complexes in this category, such as those with hydrazine and azide, for example [Zn(N2H4)2(N3)2], are of interest as primary explosives and care is needed in their manipulation. The 2,2 -dipyridylamine-azide complexes [Zn(dpa)(N3)2] and [Zn(dpa)(N3)(N03)], which have infinite 2D and 3D structures respectively, display fluorescence and phosphorescence. ... 

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]. 

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 ... 

Not yet understood is the phenomenon of spontaneous explosion in saturated azide solutions, which has been observed during crystallization of cadmium [216], copper(II) [224], mercury(II) [224], and lead [176,223,224, 280,286] azides, in both aqueous and gel media [281]. Explosions occurred at elevated as well as room temperatures [281,282]. Research so far has aimed at avoiding [282,283] or producing [284,285] the effect. In lieu of more solid advice, it may be said that the reported explosions evidently occurred in highly complexed solutions, usually containing the heavy-metal ions in excess. 

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