Nitrosyl bromide chloride

Table 3-1. Equilibrium constants Kxno (Scheme 3-28) and rate constants for diazotization of aniline (Ar2, Scheme 3-29) and of 1-naphthylamine (k2 and k-2/k Scheme 3-34) in water by nitrosyl chloride, nitrosyl bromide, nitrosyl thiocyanate, S-nitrosothiuronium ion [(NH2)2CSNO], and dinitrogen trioxide at 25 °C.

Our latest results in this field stem from a matrix-spectroscopic study of the isomerization of nitrosyl halides (152) and isonitrosyl halides (153).201 Irradiation of nitrosyl bromide (152 X = Br) and nitrosyl chloride (152 X = Cl) leads to the corresponding isomers isonitrosyl bromide (153 X = Br) and isonitrosyl chloride (153 X = Cl). Both compounds, NOBr and NOC1,202 have again been identified by comparison of the experimental and calculated (BLYP/6-311+G ) IR spectra. The back-reactions 153 - 152 can be initiated by UV, visible or IR light. Astonishingly, this retransformation also occurs spontaneously even in the matrix at 10 K under exclusion of any UV/VIS or IR radiation. 

Reactions with chlorine and bromine form nitrosyl chloride and nitrosyl bromide, respectively ... 

Nitrosyl bromide also added to imines but the yields of a-acetates after the addition of silver acetate were not better than these obtained by the addition of nitrosyl chloride. Because of their high reactivity, it was not possible to isolate a-bromodialkylnitrosamines in either case. Presumably, steric effects may also operate. 

Both gaseous products, nitrosyl chloride and nitrosyl bromide, absorb light strongly in the visible (Chapter 4) and hence photolyze readily at dawn, producing atomic chlorine and bromine, respectively. 

In a study of the addition of nitrosyl chloride or nitrosyl bromide to norbor-nene and norbomadiene, it was observed that (a) there was no structural rearrangement during the reaction, (b) a cis addition had taken place, (c) nucleophilic solvents such as ethanol or acetic acid were not incorporated in the products. These facts seem to speak against an ionic addition mechanism, while a free radical initiated by NO radicals was considered unlikely since nitric oxide is inactive toward norbomadiene. Therefore a four-center mechanism has been suggested [70], However, when a relatively simple, unstrained olefin such as A9-octalin was subjected to the reaction, only blue, crystalline, monomeric 9-nitroso-10-chlorodecalin was produced. This product had a trans configuration. Thus it is evident that the structure of the olefin has a significant bearing on the steric course of the addition [71]. 

The following two preparations illustrate the addition of nitrosyl halides to norbornene. In the first one, nitrosyl chloride itself is used in the second, nitrosyl bromide is generated in situ. 

The Nitrosyl Halogenides.—Nitrosyl fluoride, chloride, and bromide, ONF, ONC1, and ONBr, have been studied by the electron-diffraction method1 and by microwave spectroscopy.1 Their configuration is nonlinear. The N—O distance is 1.14 0.02 A. Although a reasonable electronic structure, I,... 

Fig. 3.11 Molecules with low symmetry (n) plicv pboryl bromide chloride fhiondc. C, (b nitrosyl chloride. C (c) the anu conformer of R.S-1.2-dichloro-l.2-difluoroethane.

Dichlorodinitrosylmolybdenum and tungsten have been prepared by the reaction of the appropriate hexacarbonyl with nitrosyl chloride in dichloromethane.1 The corresponding dibromo derivatives have been prepared by a similar reaction with nitrosyl bromide.2 These are the only synthetic routes to these compounds they are rapid (3 hours) and convenient. The corresponding chromium compounds are unknown. This method is a general route to transition-metal nitrosyl halide... 

In the oxide of trimethylamine, (GH3)3NO, the electron diffraction data of Lister and Sutton show that the NO bond distance is 1 36 A which is approximately the value for a single bond. If the nitrogen were penta valent, the bond would be double and the distance less and evidently, in the amine oxides, structures of the type (GH3)3N—O, make a large contribution. In nitrosyl chloride and nitrosyl bromide the NO bond length is decreased, from i ii to 1 14 A, which suggests that the bond is a hybrid of the structures... 

Nitrosyl chloride can be obtained by direct combination of chlorine with nitric oxide, by the reaction of NOHSO4 or NaNOj with HCl, or as a by-product in the preparation of KNOs from KCl and NO2, in which KCl is moistened with 2.4% water. Nitrosyl bromide is usually prepared by direct combination of bromine nuth nitric oxide. Nitrosyl chloride and nitrosyl bromide can be prepared by reacting the appropriate potassium halide with nitrogen dioxide at room temperature. The reaction rate increases with increased size of the halide, and NOCl and NOBr can be obtained in a reasonable length of time by powdering the halide salt before adding NO. ... 

Storage of nitrosyl fluoride in the glass reaction vessel containing KF is possible for a few days however, the use of an inert-metal vessel containing anhydrous KF is preferred for an extended period of time. Nitrosyl chloride is stable at room temperatxure but will always contain a small amount of NO and CU because of its reversible decomposition of 0.5%. The reversible decomposition of nitrosyl bromide is appreciable enough at room temperature (7 %) to require storage at a lower temperature, or the gas can be prepared immediately prior to use. ... 

Nitrosyl halides, at least in aqueous solutions, appear to be more potent reagents than nitrous anhydride. Schmid and his coworkers have calculated actual rate coefficients for the reaction of unprotonated amine with both molecular nitrosyl chloride and nitrosyl bromide (i.e. from the equation. Rate = A[RNH2][NOHal]). These are listed in Table 6. The characteristic features of these rate... 

Large amounts of halides, especially iodides, give only a slight greenish color under these conditions. However, 6 y thiocyanate may be detected in the presence of 1000 times the amount of iodide, bromide, chloride, thiosulfate and acetate. The latter two ions, on evaporation with cobalt salts, give a green color which, unlike that developed by thiocyanate, does not enter the acetone. Nitrites interfere because they react with thiocyanates to give red nitrosyl thiocyanate. 

Multiple-bonded molecules. Draw electronic formulas and predict the shapes of the following molecules and ions (a) nitrosyl bromide, BrNO (b) ni-tryl chloride, CINO2 (c) thionyl chloride, SOCI2 (d) SO2 (e) phosgene, CI2CO. 

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