Fulminates metal complexes

Most fulminates are very dangerously explosive, but this appears not to be the case for transition metal complexes containing tetraphenylarsonium, tetrapropylammonium or other very large cations. Much recent work on fulminate complexes has involved these compounds, and, as a result of it, the very close analogy with cyano complexes is now established beyond doubt. 

Formamidine, N,N -di-2-anthraquinonyl-metal complexes, 275 Formamidine, JV,iV -diaryl-metal complexes, 275 Formamidine, N,N -dibenzyl-metal complexes, 276 Formamidine, N,N -diisopropyl-metal complexes, 276 Formic acid metal complexes, 436 Fulminates... 

Beck and coworkers211 have reviewed transition metal complexes of the fulminate ion, CNO, which bonds to the metal via the carbon atom. Fulminate complexes are, in general, similar to those with CN ligands. An extensive series of stable, non-explosive fulminates has been examined, including [Ir(CNO)6](AsPh4)3. [Ir(CNO)6]3- was prepared from hydrated iridium(III) chloride and Hg(CNO)2, and characterized by IR spectroscopy.21"1... 

Detailed crystal structures of only a few of the other heavy metal pseudohalides are available in the literature. Among them are, cuprous azide which has a relatively simple tetragonal lattice and cupric azide, mercuric fulminate and a-lead azide which have increasingly complex orthorhombic lattices. a-Lead azide has four types of anion sites of varying amounts of as5nnmetry (33) while cupric azide (35) and mercuric fulminate (72) have two such sites. The structure of cupric azide which is built up of distorted octahedra of asymmetric Ns ions about the central cupric ion is analogous to that of a transition metal complex. 

As briefly mentioned in the previous chapter, fulminates are capable of forming a variety of complexes with metals [8, 39]. The first of the fulminato(metal) complexes (complexes with fulminate ligands) was K[Ag(CNO)2]. This compound was obtained by Liebig from the reaction of SF and potassium chloride [8]. Ammonium fulminate NH4CNO has not yet been synthesized. A complex salt containing the ammonium cation NH4[Ag(CNO)2] can be easily prepared by the reaction of the ammonium salt with SF in methanol [39]. 

The (fulminato)metal complexes are prepared from aqueous sodium fulminate solutions and transition metal salts followed by addition of tetraphenylarsonium chloride [8]. The aqueous solutions of sodium fulminate can be directly prepared from MF and sodium amalgam in water [8]. 

W. Beck Organometal Chem. Complex metal fulminates 32 ... 

Metal- and halogen-containing complexes (metal fulminates, halites, halates, etc.). 

The complex salts of precious metals, formed by the action of ammonia either on aqueous solutions of silver, gold and platinum salts or on silver oxide were the first substances tp reveal the ability to explode violently on heating, on direct contact witl flame or by friction or impact ( fulminating silver and gold). 

Hg(CNO)2 is decomposed by heat (equation 8).4 It crystallizes in the orthorhombic form and contains linearly coordinated mercury.21 It reacts with alkali metal fulminate solutions to form the highly explosive compounds M2Hg(CNO)4 (M = K, Rb, Cs) with larger cations such as Ph4As+ more stable complexes are formed.219,220 Besides the homogeneous anionic mercury(II) fulminato complexes there are a few mixed species with unknown structures, e.g. Na Hg(CNO)2X (X = Cl, Br) or Na2S203-2Hg(CNO).221... 

Nitroparaffins are sensitive to alkali, and many sensitive combinations ranging from addition complexes, through metal salts, to the very dangerous fulminates, can be formed depending on the base involved. All of these compounds are... 

The oxidation of free cyanide ion yields cyanogen or cyanate, never fulminate. It might seem that when the carbon atom is attached to hydrogen or a metal, addition of oxygen to the nitrogen atom should be possible, but there is no record of such an oxidation ever having been achieved. The reverse process, conversion of combined fulminate into combined cyanide, has, however, been demonstrated for platinum(II) and iron(ll) complexes. 

The only directly accessible metal fulminates are those of mercury(II) and silver(I), very dangerously exposive solids obtained by the action of nitric acid and ethanol on the metals or their salts. Most modern preparations of fulminato complexes involve the conversion of a known amount of mercury fulminate into aqueous sodium fulminate by the action of sodium amalgam and ice-cold water the sodium fulminate solution is then allowed to react with the appropriate amount of a transition metal salt, and the resulting complex fulminato ion is precipitated as the salt of a large cation, most frequently Ph4As+ or R4N+ these are not explosive,4,35 Alkali and alkaline earth metal salts containing complex fulminato anions may be isolated from aqueous solutions, but they are reported to be as exposive as the binary silver and mercury fulminates, and are therefore usually avoided. 

Metal cyanides(and cyano complexes), 216 Metal derivatives of organofluorine compounds, 217 IV-Metal derivatives, 218 Metal dusts, 220 Metal fires, 222 Metal fulminates, 222 Metal halides, 222 Metal—halocarbon incidents, 225 Metal halogenates, 226 Metal hydrazides, 226 Metal hydrides, 226 Metal hypochlorites, 228 Metallurgical sample preparation, 228 Metal nitrates, 229 Metal nitrites, 231 Metal nitrophenoxides, 232 Metal non-metallides, 232 Metal oxalates, 233 Metal oxides, 234 Metal oxohalogenates, 236 Metal oxometallates, 236 Metal oxonon-metallates, 237 Metal perchlorates, 238 Metal peroxides, 239 Metal peroxomolybdates, 240 Metal phosphinates, 240 Metal phosphorus trisulfides, 240 Metal picramates, 241 Metal pnictides, 241 Metal polyhalohalogenates, 241 Metal pyruvate nitrophenylhydrazones, 241 Metals, 242 Metal salicylates, 243 Metal salts, 243 Metal sulfates, 244 Metal sulfides, 244 Metal thiocyanates, 246 Metathesis reactions, 246 Microwave oven heating, 246 Mild steel, 247 Milk powder, 248... 

The list of ligands covered by Ref. 1 (vol. 2) starts with the exotic mercury ligand (Dean, p. 1). Silicon and a series of metals (Ge, Ti, Pb) (Harrison, p. 15) also reveal ligand properties. Hydrogen and a variety of hydride anion complexes (Crabtree, p. 689), as well as the complexes formed by anions with a carbon-donor center (cyanides, fulminates, etc.) (Sharpe, p. 25) are briefly discussed. 

In early days Alfred Nobel already replaced mercury fulminate (MF, see above), which he had introduced into blasting caps, with the safer to handle primary explosives lead azide (LA) and lead styphnate (LS) (Fig. 1.17). However, the long-term use of LA and LS has caused considerable lead contamination in military training grounds which has stimulated world-wide activities in the search for replacements that are heavy-metal free. In 2006 Huynh und Hiskey published a paper proposing iron and copper complexes of the type [cat]2[Mn(NT)4(H20)2] ([cat]+ = NH4, Na+ M = Fe, Cu NT = 5-nitrotetrazolate) as environmentally friendly, green primary explosives (Fig. 1.17) [3]. 

A comprehensive monograph17 on cyano complexes of the transition metals, including Fe111, is available. Cyanides and fulminates as ligands are also the subject of Chapter 12 of Volume 1 of this series.18 The ambidentate nature of the CN ion has also been reviewed.w... 

CNO The isomeric fulminate ion, CNO (Figure 3-5), can be drawn with three similar structures, but the resulting formal charges are unlikely. Because the order of electronegativities is C < N < O, none of these are plausible structures and the ion is predicted to be unstable. The only common fulminate salts are of mercury and silver both are explosive. Fulminic acid is linear HCNO in the vapor phase, consistent with structure C, and coordination complexes of CNO with many transition metal ions are known with MCNO structures. ... 

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