Nitrogen, ions with

Pfandzelter R, Bernhard T, Winter H (2001) Spin-polarized electrons in collisions of multi-charged nitrogen ions with a magnetized Fe(001) surface. Phys Rev Lett 86 4152... 

The authors of Refs [15] and [16] also observed a substantial loss of nitrogen in a chromium coating due to spattering, when intensive beams of nitrogen ions with the energy of 1 keV were used. In the latter case, the energy was rather high and it reached 20 keV, and the beam density was also substantial and was equal to 440 pA/cm. ... 

Implant with nitrogen ions with the appropriate energy and fluence to induce the desired conductivity,... 

Determine the charge of each ion. (a) oxygen ion with 10 electrons (b) aluminum ion with 10 electrons (c) titanium ion with 18 electrons (d) iodine ion with 54 electrons 74. Determine the charge of each ion. (a) tungsten ion with 68 electrons (b) tellurium ion with 54 electrons (c) nitrogen ion with 10 electrons (d) barium ion with 54 electrons... 

Tree, 1987). Concerning the problem of interstellar ammonia formation, the low temperature measurements demonstrate that the reaction of atomic nitrogen ion with hydrogen is not an efficient route. Therefore it is still a problem to explain ammonia abundance in interstellar clouds. 

It is essential to use an excess of sodium, otherwise if sulphur and nitrogen are both present sodium thiocyanate, NaCNS, may be produced in the test for nitrogen it may give a red coloration with ferric iron but no Prussian blue since there will be no free cyanide ions. With excess of sodium the thiocyanate, if formed, will be decomposed ... 

We shall now consider the implications of these newer results for the nitration of these cations, taking first the comparison of the anilinium ion with its increasingly methylated homologues, then the various cations containing the trimethylammonio group, and finally cations containing elements other than nitrogen. 

Substituted ammonium ions derived from nitrogen bases with names ending in -amine receive names formed by changing -amine into -ammonium. When known by a name not ending in -amine, the cation name is formed by adding the ending -ium to the name of the base (eliding the final vowel) e.g., anilinium, hydrazinium, imidazolium, acetonium, dioxanium. 

Ion implantation (qv) direcdy inserts nitrogen into metal surfaces. A carefully poHshed and cleaned metal surface at room temperature in a vacuum (-- 0.133 mPa (l-) m Hg)) can be directly implanted with 80-keV nitrogen ions (10) (see Metal surface treatments, case hardening). In an alternative synthesis, argon ions (Ar ) of 8 keV can be used to ionize gas-phase nitrogen to obtain the same results (17). 

By far the most important metal containing dyes are derived from OjO-dUiydroxyazo stmctures in which one of the two azo nitrogen atoms and the two hydroxyl oxygen atoms are involved in bonding with the metal ion. Thus these dyes serve as terdentate ligands. In the case of metal ions with a coordination number of four, eg, Cu(H), the fourth position is usuaUy occupied by a solvent molecule (47). 

The reaction of A-acyliminium ions with nucleophilic carbon atoms (also called cationic x-amidoalkylation) is a highly useful method for the synthesis of both nitrogen heterocycles and open-chain nitrogen compounds. A variety of carbon nucleophiles can be used, such as aromatic compounds, alkcncs, alkyncs, carbcnoids, and carbanions derived from active methylene compounds and organometallics. 

For reactions of A-acyliminium ions with alkenes and alkynes one has to distinguish between A-acyliminium ions locked in an s-trans conformation and those which (can) adopt an s-cis conformation. The former type reacts as a (nitrogen stabilized) carbocation with a C —C multiple bond. Although there are some exceptions, the intramolecular reaction of this type is regarded as an anti addition to the 7t-nucleophile, with (nearly) synchronous bond formation, the conformation of the transition state determining the product configuration. 

In the literature discussing these results, the coincidence of the NN bond lengths in diazonium ions with that in dinitrogen seems always to be regarded with complete satisfaction. In the opinion of the present author this close coincidence is somewhat surprising, firstly because of the fact that in diazonium ions one of the nitrogen atoms is bonded to another atom in addition to the N(2) atom, and secondly because work on dual substituent parameter evaluations of dediazoniation rates of substituted benzenediazonium ions clearly demonstrates that the nx orbitals of the N(l) nitrogen atom overlap with the aromatic 7t-electron system (see Sec. 8.4). 

Bagal (1974) studied the influence of substituents on the ground and first excited states of arenediazonium ions. With regard to compounds in which mesomeric structures such as 4.1b are important, these authors are skeptical about the validity of the PP method. Later, Bagal et al. (1982) used CNDO/2. The calculated 7r-electron densities at all the nitrogen and carbon atoms were similar to those in the earlier PP results. 

The conductometric results of Meerwein et al. (1957 b) mentioned above demonstrate that, in contrast to other products of the coupling of nucleophiles to arenediazonium ions, the diazosulfones are characterized by a relatively weak and polarized covalent bond between the p-nitrogen and the nucleophilic atom of the nucleophile. This also becomes evident in the ambidentate solvent effects found in the thermal decomposition of methyl benzenediazosulfone by Kice and Gabrielson (1970). In apolar solvents such as benzene or diphenylmethane, they were able to isolate decomposition products arising via a mechanism involving homolytic dissociation of the N — S bond. In a polar, aprotic solvent (acetonitrile), however, the primary product was acetanilide. The latter is thought to arise via an initial hetero-lytic dissociation and reaction of the diazonium ion with the solvent (Scheme 6-11). 

Fig. 7-2. Potential energy E as a function of the reaction coordinate for reactions of the P-nitrogen of arenediazonium ions with nucleophiles yielding (Z)- and (is)-azo compounds, a) Reactant-like transition states (e. g., reaction with OH) b) product-like transition states (e. g., diazo coupling reaction with phenoxide ions product = cyclohexadienone-type o-complex (see Sec. 12.8).

The reaction with nitrite proceeds smoothly and with relatively high yields of the corresponding nitroarene (see Sec. 10.6). Obviously a major part of the driving force of this reaction is the formation of a stable, i. e., an energetically favorable, radical, nitrogen dioxide. With the hydroxide ion — a much stronger nucleophile than the nitrite ion — the reaction is expected to produce very unstable radicals, the hydroxy radical OH and the oxygen radical anion O, from the diazohydroxide (Ar - N2 — OH) and the diazoate (Ar-N20 ) respectively. Consequently, dediazoniation in alkaline aqueous solution does not follow the simple Scheme 8-41 with Yn = OH, but instead involves diazoanhydrides (Ar — N2 —O —N2 —Ar) as intermediates (see Sec. 8.8). 

A true intramolecular proton transfer in the second step of an azo coupling reaction was found by Snyckers and Zollinger (1970a, 1970b) in the reaction of the 8-(2 -pyridyl)-2-naphthoxide ion (with the transition state 12.151). This compound shows neither a kinetic deuterium isotope effect nor general base catalysis, in contrast to the sterically similar 8-phenyl-2-naphthoxide ion. Obviously the heterocyclic nitrogen atom is the proton acceptor. 

---