Nitrogen Pentavalent

Figure 2-52. a) Two semipolar resonance structures are needed in a correct VB representation of the nitro group, b) Representation of a nitro group by a structure having a pentavalent nitrogen atom, c) The RAMSES notation of a nitro group needs no charged resonance structures. One jr-system contains four electrons on three atoms. 

Cation is water repellent based on pentavalent nitrogen... 

Quaternary ammonium salts are organically substituted nitrogen compounds in which the nitrogen atom is pentavalent. Four of the substituents are alkyl, aryl or heterocyclic radicals and the fifth is an anion (a cationic charge). This anion is mostly chloride. Therefore we call them benzalkonium chlorides. 

The solids considered in this section are phosphorus oxynitrides and nitridooxophosphates. They are pentavalent phosphorus(V) compounds and correspond to a partial substitution of nitrogen, under the nitride form N3, for oxygen 02 within P04 tetrahedra, resulting in the formation of mixed P(0, N)4 tetrahedra. 

Nitrate ISEs can also be used for determination of nitrogen oxides after oxidation to the pentavalent form (for example with H2O2) [39, 41, 101, 109, 150]. The nitrate ISE system is also useful for 2,4-dichlorophenoxyacetate [73] and for tetrathionate [215]. 

The metal is attacked by mineral acids. Reactions with sulfuric and hydrochloric acids produce hydrogen. With nitric acid, no hydrogen is evolved but the pentavalent nitrogen is reduced to nitrogen at lower valence states. 

Table VI. Homologation of Methyl Acetate to Ethyl Acetate Effects of Pentavalent Phosphorus and Nitrogen Compounds...

These workers showed that dissolved arsenic and antimony in natural waters can exist in die trivalent and pentavalent oxidation states, and the biochemical and geochemical reactivities of these elements are dependent upon their chemical forms. They developed a method for the simultaneous determination of arsenic (III)+antimony (III+V)+ antimony (III+V) that uses selective hydride generation, liquid nitrogen cooled trapping, and gas chromatography-photoionisation detection. The detection limit for arsenic is lOpmol L 1 while that for antimony is 3.3pmol L 1 precision (as relative standard deviation) for both elements is better than 3%. 

Synthetically useful phosphorane-derived phenyliodonium triflates have been synthesized from the highly electrophilic pyridinium complex 20 <2002TL2359>. Similarly, benziodoxole 21 reacts with trimethylsilyl trifluoro-methanesulfonate (TMSOTf) and pyridine to form a precipitate of complex 22 (Equation 6) <2002TL5735>. The first example of a pentavalent iodine complex with a chelating polydentate nitrogen ligand 24 was obtained from diacetate 23 under similar conditions (Equation 7) <2002TL5735>. 

In an attempt to demonstrate the existence of pentavalent nitrogen, Schlenk and Holtz studied the reaction of triphenylmethyl sodium with tetramethylammonium chloride (52). The highly colored material was strongly conducting in polar solvents and could be identified as a salt, the stability of which is due to the resonance stabilization of the triphenyl-methide anion. In the absence of such stabilizing substituent effects (53), as with n-butyl or another alkyllithium reagent, a metalation of the tetramethylammonium cation occurs, which leads to type I products (18) ... 

As already mentioned (105), no pentavalent nitrogen compound NRg has ever been reported. In view of the present knowledge of the valence... 

In connection with some work that we are doing on the constitution of the proteins, it became essential to know in what cases nitrogen in organic compounds will or will not add on hydrogen chloride gas stoichio-metrically at room temperature and atmospheric pressure to give what is ordinarily called pentavalent nitrogen. 

VII. If the nitrogen is already pentavalent through formation of an intramolecular salt, hydrogen chloride can only be taken up stoichiometrically in case it displaces the other acid. 

Under VI we find that hydrogen chloride does add reversibly and stoichiometrically to hydrocyanic acid, but not to give pentavalent nitrogen. It forms amino-formyl chloride, H2C(C1) NH. This substance would undoubtedly add hydrogen chloride to the nitrogen if it did not polymerize. The polymerization products of the nitriles, isonitriles, cyanates and isocyanates have not been studied with any satisfactory degree of care. 

The electrophilic substitution is straightforward, occurring in the para position on the activated hindered dialkylamine. Notice that nucleophilic attack must occur on the end nitrogen atom of the diazonium salt to avoid forming pentavalent nitrogen. 

Antimony forms nnmerons stable pentavalent organo-metallic componnds among these are penta alkyls and aryls, mixed organohalides, and varions chalcogen and nitrogen derivatives. 

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