Fulminate , structures

The fulminates (containing the CNO group or ion) and the cyanamides (CN3 ) bear some structural similarities to the azides. 

The fulminate ion, CNO-, probably has a structure intermediate between C N O and C N 6 for since these two bond types have the same bond angles and term symbols ( 2), they can form intermediate structures lying anywhere between the two extremes. Which extreme is the more closely approached could be determined from a study of the bond angles in un-ionized fulminate molecules, such as AgCNO or ONCHgCNO, for the first structure would lead to an angle of 125° between the CNO axis and the metal-carbon bond, the second to an angle of 180°. 

Both structures II and III have an arrangement of atoms that places a positive formal charge on atoms that are higher in electronegativity than carbon. Consequently, the most stable arrangement of atoms is as shown in structure I. Some compounds containing the ion having structure III (the fulminate ion) are known, but they are much less stable than the cyanates (structure I). In fact, mercury fulminate has been used as a detonator. 

Addition of ammonia as a model nucleophile to nitrile oxides was studied by a semiempirical MNDO method, for fulminic acid and acetonitrile oxide (121). The reaction is exothermic and proceeds in two steps. The first (and rate-determining) step is the formation of a zwitterionic structure as intermediate. The second step, which involves transfer of a proton, is very fast and leads to the formation of Z-amidoximes in accordance with experimental data. Similar results were... 

C) A. Suzuki, Crystalline Structure and Ex-plosibility of Fulminate of Mercury , US Air Technical Branch Rept 0418 (1944)... 

Fulminate de mercure in Fr Knallquecksilber in Ger Fulminato di metcurio in Ital Fulminato de mercurio in Span Gremuchaya rtut in Russ and Raiko or Raisan suigin (Thunder Mercury) in Japan], Hg(ONC)2- Structural formula not established. Pepin Lehalleur (Addnl Ref J, p 141) proposed Hg(ON C)2 and that of Scholl... 

N 49 01% wh ndls, sol in warm w. Structure not known. Prepd by heating Mercury Fulminate with ammonia at 70°. Completely decomposed to CO2 and NHa by dil HCl at 150°. Neutral in water, but will react with metal oxides giving, eg, a Silver salt, Ag/)6HgN903 Refs 1) Beil 1, 723 2) A. Steiner, Ber 8 ... 

This kind of structure is also proved by the fact that chemically fulminic acid behaves as an unsaturated compound, adding hydrogen chloride at a temperature of 0°C, to form the crystalline chloroformoxime (VI) ... 

According to Patry [22] fulminate darkens under the influence of irradiation by a mercury arc. After a month test samples become almost black and the mercury content increases from 70.8 to 71.3. As on heating, the crystalline structure remains unchanged but the optical properties of the crystals undergo alteration. 

Silver fulminate was recognized by Gay-Lussac16 to have the same composition as silver cyanate, thus providing the first example of isomerism. Two polymorphs of silver fulminate are known and their structures have been determined.17 Silver fulminate is regarded as a poor detonator due to its dangerous sensitivity this may depend on the presence or absence of the second form.17... 

Both the cyanide, [Au(CN)2] , and fulminate, [Au(CNO)2] , ions contain linear gold(I) centres.387,388 A report that KAu(CN)2(2,2 -bipyridyl) contains square planar gold(I) has been disproved the bipy ligand is not coordinated to gold and the complex contains linear [Au(CN)2J ions. 390 AuCN is polymeric with a linear (—Au—CN—) Au— chain structure.391... 

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... 

By means of a synthesis of isoxazol derivs with fulminic acid, it was establish that the structure of the acid reported in Ref a is incorrect. It should be 3-isoxazole carboxylic acidl... 

The pyrolysis of 4//-isoxazolin-5-ones of general structure 323 proceeds readily with loss of CO2 and RCN to give the corresponding carbenes X=C . This has provided a convenient route for the generation of fulminic acid, HO—N=C , by pyrolysis of oximes... 

Two explosions during the crushing of the cyanate are recorded [1]. Once the standard preparation of cyanogen (qv) was by pyrolysis of this salt - the method was abandoned after explosions attributed to fulminate impurities. Now that the structure of fulminates has been established, isomerisation of cyanate to give fulminate as impurity is no longer credible [2],... 

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