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Showing papers on "Triazene published in 1986"


Book ChapterDOI
TL;DR: In this article, the first transition metal derivatives of tetrazadienes were discussed, including a binuclear tungsten derivative of the hypothetical iso-tetrazene molecule (H 2 N) 2 N=N.
Abstract: Publisher Summary The observation that, with a few notable exceptions, coordination to transition metals imparts stability to catenated nitrogen systems promises exciting developments in the future. Although organic molecules containing up to 10-linked nitrogen atoms have been synthesized, metal complexes are known to date only for systems containing 2-, 3-, 4- , or 5-nitrogen chains. The chemistry of two-nitrogen ligands-notably hydrazines, diazenes, and, of course, dinitrogen itself- has received an enormous boost in recent years from the work on nitrogen fixation. The three-nitrogen systems include, in addition to the azide anion, triazenes, and their N-oxides. Complexes containing ArN=N–N(Ar)C(O) or “phosphazide” (ArN=N–N=PR 3 ) ligands are presented. The chemistry of four-nitrogen ligands is dominated by complexes of tetrazadienes, RN=N–N=NR, which are discussed together with the few isolated examples of tetrazene derivatives. The latter include a binuclear tungsten derivative of the hypothetical iso-tetrazene molecule (H 2 N) 2 N=N. The chapter discusses the first transition metal derivatives of pentazadienes RN=N–N(H)–N=NR. Cyclic catenated nitrogen ligands are also discussed. Diaryl-, alkylaryl-, and, to a lesser degree, dialkyltriazenes are readily available. Consequently most triazenide complexes are synthesized from the free triazene or one of its salts. The chapter presents examples of the applications of spectroscopic techniques to the study of tetrazadiene complexes.

78 citations


Journal ArticleDOI
TL;DR: Biological evaluation of two pyrazolotetrazine derivatives synthesized as the analogous prodrugs of the light-sensitive antineoplastic agents dacarbazine and BIC revealed that the compound containing a 2-chloroethyl function demonstrated good antineopolastic activity in experimental animals, but the one containing a methyl function was inactive.
Abstract: Two pyrazolotetrazine derivatives were synthesized as the analogous prodrugs of the light-sensitive antineoplastic agents dacarbazine and BIC. Both the pyrazole derivatives are stable under ordinary light illumination. Biological evaluation of these pyrazoles revealed that the compound containing a 2-chloroethyl function (6a) demonstrated good antineoplastic activity in experimental animals, but the one containing a methyl function (6b) was inactive. The inactivity of compound 6b may suggest that compound 6a and related imidazotetrazines may simply act as biological alkylating agents per se rather than as prodrugs. The information could also imply that the postulated dealkylation mechanism for the triazene derivatives should be reexamined.

25 citations


Journal ArticleDOI
TL;DR: In this paper, the mechanism of the protodediazoniation is shown to involve transfer of the formyl hydrogen atom to the substrate and may proceed via a 1-aryl-3-formyltriazene.
Abstract: Treatment of preformed arenediazonium tetrafluoroborates or arenediazonium trifluoroacetates (formed in situ) with formamide and base effects reduction to the corresponding arene in moderate to good yield in cases where an electron-withdrawing substituent is present on the aromatic ring. Other functionalities remain unaffected. The mechanism of the protodediazoniation is shown to involve transfer of the formyl hydrogen atom to the substrate and may proceed via a 1-aryl-3-formyltriazene.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the thermal decomposition of 2-carboxyaryl triazenes was used to generate 4-methyl, 4-chloro and 4-bromo derivatives of Benzyne.

7 citations


Journal ArticleDOI
TL;DR: The mechanism for the reaction of 1,3-diaryltriazenes with tetracyanoethylene (TCNE) in the presence of acetic acid, giving Schiff's bases and arylhydrazonomalonononitriles, has been investigated in this article.
Abstract: The mechanism for the reaction of 1,3-diaryltriazenes with tetracyanoethylene (TCNE) in the presence of acetic acid, giving Schiff's bases and arylhydrazonomalononitriles, has been investigated. The intermediacy of arylazomalononitriles was confirmed by crossover experiments using an arylamine different from the component of the triazene. The route to the azo compounds via TCNE–triazene adducts had already been established by a tracer experiment using an 15N-labelled triazene. However, the crossover experiments, as well as the result of the reaction of a triazene with the TCNE–2,6-dimethylaniline adduct, revealed an alternative route via TCNE–ArNH2 adducts in the presence of acetic acid.

6 citations


Journal ArticleDOI
TL;DR: In this article, 3-aryl-1-(tetrazol-5′-yl) triazenes (4) with lead tetra-acetate resulted in a fragmentation to aryl diazocyanides.
Abstract: Treatment of 3-aryl-1-(tetrazol-5′-yl)triazenes (4) with lead tetra-acetate resulted in a fragmentation to aryl diazocyanides. The triazenes (4) and their monomethyl derivatives when treated with mercuric acetate and phenylmercury hydroxide gave stable mercuri compounds with mercury bonded at N-3 and the tetrazole N-2′. The reaction of the triazenes with acetic anhydride resulted in acetylation of the triazene unit with fragmentation to aryl diazonium ions and 5-acetamidotetrazoles. These reactions are discussed and the 13C n.m.r. spectra of the products are analysed.

4 citations


Journal ArticleDOI
TL;DR: The metallacycle [Br₃WS₂N₆] was obtained from the reaction of S₄N� with WBrↅ.
Abstract: The metallacycle [Br₃WS₂N₃] has been obtained from the reaction of S₄N₄ with WBr₅. The salt [Ph₄P⁺][Br₄WS₂N₃⁻] was formed from [Br₃WS₂N₃] by addition of Ph₄PBr. It crystallizes in the orthorhombic space group Pbca with a = 1396.8(4), b = 1961.9(5), c = 2108.0(4) pm, and Z = 8. The following mean bond lengths were observed in the anion: W-N 184.2, W-Br 256.8, N-S 157.8 pm.

2 citations


Journal ArticleDOI
TL;DR: Triazene formation was partly inhibited in the presence of vegetable juice, and there was a high positive correlation between the nitrite concentration in the saliva and the triazene yield.

1 citations