Nitrogen species

Ring closures which depend on the conversion of the heteroatom into an electrophile are mostly associated with the formation of thiophene, selenophene and tellurophene rings and some illustrative examples are shown in Scheme 17. The last example which concerns the conversion of reaction with isocyanides is of particular interest since it appears to entail the attack of an electrophilic nitrogen species on the aryl ring. 

Prompt NO Hydrocarbon fragments (such as C, CH, CH9) may react with atmospheric nitrogen under fuel-rich conditions to yield fixed nitrogen species such as NH, HCN, H9CN, and CN. These, in turn, can be oxidized to NO in the lean zone of the flame. In most flames, especially those from nitrogen-containing fuels, the prompt... 

R. Mews, P. G. Watson and E. Lork, Three-coordinate Sulfur(VI)-Nitrogen Species An Attempt to Breathe Some New Life into an Old Topic, Coord. Chem. Rev., 158, 233 (1997). 

T. M. Klapotke, Binary Selenium-Nitrogen Species and Related Compounds, in R. Steudel (ed.) The Chemistry of Inorganic Ring Systems, Elsevier, pp. 409-427 (1992). 

Cycloaddition reactions also have important applications for acyclic chalcogen-nitrogen species. Extensive studies have been carried out on the cycloaddition chemistry of [NSa]" which, unlike [NOa]", undergoes quantitative, cycloaddition reactions with unsaturated molecules such as alkenes, alkynes and nitriles (Section 5.3.2). ° The frontier orbital interactions involved in the cycloaddition of [NSa]" and alkynes are illustrated in Fig. 4.13. The HOMO ( Tn) and LUMO ( r ) of the sulfur-nitrogen species are of the correct symmetry to interact with the LUMO (tt ) and HOMO (tt) of a typical alkyne, respectively. Although both... 

Unlike reactive diatomic chalcogen-nitrogen species NE (E = S, Se) (Section 5.2.1), the prototypical chalcogenonitrosyls HNE (E = S, Se) have not been characterized spectroscopically, although HNS has been trapped as a bridging ligand in the complex (HNS)Fc2(CO)6 (Section 7.4). Ab initio molecular orbital calculations at the self-consistent field level, with inclusion of electron correlation, reveal that HNS is ca. 23 kcal mof more stable than the isomer NSH. There is no low-lying barrier that would allow thermal isomerization of HNS to occur in preference to dissociation into H -1- NS. The most common form of HNS is the cyclic tetramer (HNS)4 (Section 6.2.1). 

Table 11.4 Standard reduction potentials for nitrogen species in acidic aqueous solution (pH 0, 25°C)...

Numerous charged sulfur-nitrogen species have been synthesized in recent years, particularly those having an odd number of N atoms which would otherwise be paramagnetic. However, thio analogues of nitrites (N02, p. 461) and nitrates (N03, p. 465) are unknown. 

In most cases, the direct reaction of N2 with O2 is slow under ambient conditions. It is the presence of numerous odd electron species (for example, OH, HO2, and RO2 radicals) that are photochemically produced and responsible for most of the oxidizing reactions of nitrogen species in the atmosphere. Some of the important reactions are shown below ... 

Lawson, D. R. (1988). The nitrogen species methods comparison study An overview. Atmos. Environ. 22,1517. 

Stedman, D. H. and Shelter, R. E. (1983). The global budget of atmospheric nitrogen species. In "Trace Atmospheric Constituents" (S. E. Schwartz, ed.). Wiley, New York. 

Hinson, J.A. Reid, A.B. McCullough, S.S. James, L.P. (2004). Acetaminophen-induced hepatotoxicity role of metabolic activation, reactive oxygen/nitrogen species, and mitochondrial permeability transition. Drug Metabolism Reviews, Vol.36, No. 3-4, (January 2004), pp. 805-822, ISSN 0360-2532. 

Wiseman H, Halliwell B Damage to DNA by reactive oxygen and nitrogen species role In Inflammatory disease and progression to cancer. BlochemJ 1996 313 17. 

Carotenoid reactions with ROS or RNS (reactive nitrogen species) would generate prooxidative products. ... 

Brennan M-L and et al. (2002) A tale of two controversies. Defining both the role of peroxidases in nitrotyro-sine formation in vivo using eosinophil peroxidase and myeloperoxidase-deficient mice, and the natnre of the peroxidase-generated reactive nitrogen species. J Biol Chem 277 17415-17427. 

Research on plasma-deposited a-C(N) H films has been frequently included in the general discussion of carbon nitride solids [2, 3]. However, the presence of hydrogen in its composition, and the complexity of the deposition process, which introduces the nitrogen species in the already intricate hydrocarbon plasma-deposition mechanism, make a-C(N) H films deserve special consideration. This is the aim of the present work to review and to discuss the main results on the growth, structure, and properties of plasma-deposited a-C(N) H films. As this subject is closely related to a-C H films, a summary of the main aspects relative to the plasma deposition of a-C H films, their structure, and the relationship between the main process parameters governing film structure and properties is presented... 

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