Tetrazenes cyclic

The interesting "dimerization of lithiated N-nitrosamines to cyclic tetrazene N-oxides has been described (U8) and provides another route to the novel cyclic tetrazenes (U9, 0) A radical path has been suggested for this reaction [Scheme h] ( ). 

This review, which complements an earlier one (Part I) dealing with transition metal complexes of triazenes, tetrazenes, tetraazadienes, and pentaazadienes, examines the coordination chemistry of related cyclic catenated nitrogen ligands. Six-membered rings containing three, four, or five adjacent nitrogen atoms — 1,2,3-triazines, 1,2,3,4-tetrazines, and pentazines, respectively — are either unknown or are relatively unstable species whose coordination chemistry has yet to be explored. 

Thermolysis of tetrazene 2 in cyclohexane has been reported to give the cyclic pyrrolidine and, presumably, the piperidine in 41 and 16% yields, respectively [Eq. (2)]. The formation of these reduced products must result... 

The cyclization of aminyl radical 5, produced by decomposition of tetrazene 4 (Scheme 1), was investigated, and products were analyzed by GC/MS comparisons to authentic materials. The results are summarized in Table 1 (83JA7759). It is important to note that no piperidine products were detected and that a 1 1 ratio of cyclic-to-acylic disproportionation... 

The reaction between aryl azides and lithiated aryl amines leads to tetrazenes, which give cyclic silatetrazenes with halosilanes (equation 7)17. Also, the new mono-, bis- and tris-silylamines 15-28 were obtained18-22. The hydrazine 16 was analyzed by electron and X-ray diffraction18. 

The tetrazene syntheses [Eq. (35) and path (a), Eq. (37)] develop according to the general scheme IW + NN - NNNN. One possible synthesis of Group IV derivatives of tetrazene according to scheme N + NNN - NNNN consists of [2 + 3]-cycloaddition of azides to sila- or germaketimines (stannaketimines are still not known) to form cyclic tetrazenes 34 (sila- or germatetrazolines) [Eq. (38)] (Preparation... 

Cis-silylated, germylated, or stannylated acyclic tetrazenes have not yet been identified (33). These are, probably in all cases, substantially higher in energy than the corresponding trans compounds. The cyclic tetrazenes (sila- and germatetrazolines) listed in Table III, however, are in the cis configuration. 

An example of substitution followed by cyclization of the substituted tetrazene has been observed in the reaction of (Me3Si)4N4 with phenylsul-fonyl isocyanate [Eq. (76)] (45), leading to cyclic tetrazene 61, which also is obtainable by the action of CO2 on MesSi—N=N—SiMes, cf. ref. 56.]... 

Thermolysis of the hexenyl tetrazene in cyclohexane gave the following cyclic products. 

No cyclic products were obtained from either the photolysis or the thermolysis of the butenyl tetrazene, F. The principal isolated product in the photochemical reaction was the parent amine, N-propyl-N- 3-butenyl)amine, formed in about 50 percent yield. In the thermolysis reaction the principal reaction was the 6-scission. 

The cis-cyclic tetrazene was formed in 5 percent yield by basic oxidation of the precursor dihydrazine (R Me) with sodium hypochlorite. A general synthesis of tetrazenes of this type was worked out by Seebach and co-workers (, 58, ). The... 

The rapid decomposition of N2H2, generated in situ in solution (e.g. in ether) into N2 and N2H4 in the absence of a reactive substrate, can be Interpreted as self-reduction via a cyclic intermediate complex. Only under extremely basic conditions nearly complete decomposition into N2 and H2 Is observed, probably via N2H2 + OH - H2O + N2H", N2H" N2 + H, and H -I- HB -)>H2 + B" [15, 16]. The acid-catalyzed decomposition in ethereal solution at low temperatures leads to dimerization via tetrazene to NH4N3 [17]. 

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