Nitrosyl halide

Nitrosyl Halides.26 The exothermic reactions of I(52Py2) with NOC1 and NOBr19,145 

Submitted by CHARLES T. RATCLIFFE and JEAN NE M. SHREEVE Cheeked by KENNETH J. WYNNEf 

The synthesis of nitrosyl fluoride has been previously carried out by burning nitric o. ide and fluorine at low temperatures in a 

Huorothene vessel. Other methods include the decomposition of various nitrosyl adducts. In the present method, nitrogen dioxide is allowed to react at room temperature with an excess of potassium fluoride to produce nitrosyl fluoride, in nearly quantitative yields, as the only volatile product. The rate of formation of nitrosyl fluoride may be dramatically increased by first forming a potassium fluoride-hexafluoroacetone adduct which is subsequently thermally decomposed to yield potassium fluoride having a high surface area. 

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.  

For 4-electron 3-centre bonding units, the increased-valence structure (11) can also be constructed by spin-pairing the unpaired electron of atom B with the 

We shall now use increased-valence structures, with Pauling 3-electron bonds as components, to discuss the electronic structures for a number of molecules that have NO, OO, SS, SO or NOj linkages. Bond-lengths for them are reported in Tables 11-1 to 11-4. 

The length of the N-0 bond of FNO is 1.136 A, which is similar to the length of 1.150 A for the free NO molecule. This observation suggests that we might obtain a suitable valence-bond structure for FNO by bonding a fluorine atom to the Pauling 3-electron bond structure 13 (Section 4-5) for NO. 

Chapter 11 Pauling 3-Electron Bonds and Increased-Valence Structures 

To obtain increased-valence structure (14), we have spin-paired the nitrogen odd-electron charge of structure (13) with a corresponding fiaction of the fluorine unpaired electron. Because (5) = (6) (7), valence-bond structure (14 )is equi- 

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Nitrogen forms two series of oxohalides — the nitrosyl halides XNO and the nitryl halides XNO2. There are also two halogen nitrates FONO2 (bp -46°) and CIONO2 (bp 22.3°), but these do not contain N-X bonds and can be considered as highly reactive derivatives of nitric acid, from which they can be prepared by direct halogen ation ... 

The nitrosyl halides are reactive gases that feature bent molecules they can be made by direct halogenation of NO with X2, though fluorination of NO with Agp2 has also been used and CINO can be more conveniently made by passing N2O4 over moist KCl ... 

Such reactions provide an excellent route to anhydrous metal nitrates, particularly when metal bromides or iodides are used, since then the nitrosyl halide decomposes and this prevents the possible... 

The stable molecular nitrosyl halides NOX (p. 442) and phosphoryl halides POX3 (p. 501) find few counterparts in the chemistry of As, Sb and Bi. AsOF has been reported as a product of the reaction of AS4O6 with ASF3 in a sealed tube at 320° but has not been fully characterized. ASOF3 is known only as a polymer. Again, just as AsClj eluded preparation for over 140 y after Liebig s first attempt to make it in 1834, so... 

Schmid s observation of the dependence of the reaction rate on the square of the concentration of nitrous acid was interpreted by Hammett (1940, p. 294) as due to the rate-limiting formation of dinitrogen trioxide, N203. The consequent attack of the amine by N203 was postulated to be faster therefore the concentration of the amine has no influence on the overall rate (zero order with respect to amine). Similarly, Hammett regards the second factor of Schmid s equation for diazotization in the presence of hydrochloric or hydrobromic acid as the result of the formation of nitrosyl halide. 

The rate-limiting step in diazotizations with nitrosyl halides can in some cases be the formation of the nitrosyl halide (Scheme 3-26) this occurs with very reactive aniline derivatives (Hughes and Ridd, 1958). Alternatively it can be the deprotona-... 

A number of gaseous oxyhalides of nitrogen are known, including the types XNO (nitrosonium or nitrosyl halides) with X = F, Cl, or Br, and XN02 (nitryl halides) with X = F or Cl. Nitrosonium halides are prepared by the reactions of halogens and NO. 

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. 

There are numerous examples of the demonstration of the catalytic activity of thiocyanate ion for a wide variety of substrates. In general the reaction of ONSCN is rate-limiting, but in some cases (just as for the nitrosyl halides) with very reactive substrates the formation of ONSCN can be rate-limiting. 

Nitroso compounds are formed during the addition of nitrous oxide," " dinitrogen trioxide, and nitrosyl halides to alkenes, and in some cases, from incomplete oxidation of amines with peroxyacids like peroxyacetic acid. Quenching of carbanions with nitrosyl halides is also a route to nitroso compounds. A full discussion on this subject is beyond the scope of this work and so the readers are directed to the work of Boyer. ... 

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. 

Somewhat analogous to the Reed process is a recent development in which an olefin is reacted with nitrosyl chloride to form a nitrosyl halide, which in turn is converted to a mixture of complex sulfonates by reaction with sodium sulfite (4). These materials are reported to be excellent metal cleaning detergents. 

The halide complexes are more easily made from the nitrosyl halides and halides, thus... 

Diazotization is a complex reaction (Scheme 1). When performed in acidic media with sodium nitrite, NOx or nitrosyl halides, its kinetics are dependent upon the acidity of the medium in media with a Hammett acidity constant (-H0) from — 1 to 3 the reaction rate increases with acidity and the formation of the nitroso cation is the rate-limiting step, in more acidic media (-H0 > 4) the reaction rate decreases when acidity increases and the deprotonation of intermediate 6 is the rate-limiting step.6-9... 

Basco and Norrish24 irradiated C1NO and BrNO with radiation at wavelengths near 2500 A. The nitrosyl halide decomposed to the halogen atom and vibrationally excited NO... 

In a lecture presented to the Faraday Society,332 Norrish commented on why the higher vibrational levels of NO were observed in the nitrosyl halide experiments but not by absorption in NO irradiation experiments. He reasoned that, as the emission of NO from the AZH + state populates the first five vibrational levels of NO almost equally,341 the fast-exchange reaction (4) can quickly eliminate all the vibrational levels above the first. However, in the nitrosyl halide experiments, the NO may be formed preferentially in very high levels, such as v — 10 or 11, almost exclusively. Thus, reaction (4) cannot occur initially, and depopulation must be by reaction (2). Reaction (2) is considerably slower than reaction (4), because of the increased difference in vibrational energy between the reactants and products resulting from an-harmonic effects. 

Nitrosyl halides (or dinitrogen tetroxide acting as N0+N03 ") can also displace carbonyl groups. The metal nitrosyl halides which result are often polymeric in nature. 

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