Group IV Derivatives of Tetrazene

Organic tetrazenes can be formed in high yield by the oxidation of l,l-bis(organyl)hydrazines R2N—NH2 (31). On the other hand, bis(silyl)hydrazine (31) is converted only indirectly [Eq. (34)] to tetra-kis(silyl)tetrazene (32) (1, 32, 33). The last synthetic step, involving dimerization of azosilane, shows low yield thermally, but high yield (90%) in the presence of the Lewis acid Sip4 as catalyst. 

McaSi r-BuMe2Si r-Bu2MeSi t-BuaSi PhaSi McaC p-Tol 

Another method for synthesizing Group IV derivatives of tetrazenes by constructing nitrogen chains depends on coupling of hydrazides with aryldiazonium salts (Preparation Method G). Thus, the reaction of ArN2Cl (Ar = Ph, p-Tol) with lithium tris(trimethylsilyl)hydrazide in diethyl ether leads to 1-tetrazene (33) in 50% yield [path (a), Eq. (37)]. At the same 

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 

Method H). Thus, the reaction of sila- or germaketimines Mc2E=NR (R = SiMe f-Bu3 , SiPh3 prepared by the thermolysis of silatriazoiines, Section II,C,2) with azides RN3 (R = Mc3C, Me t-Bu3 Si) proceeds smoothly to [2 + 3]-cycloadducts 34 with Mc2E ring members (15,16, 40) (for individual compounds see Table III). 

McsSi t-BuMe2Si t-BujMeSi t-BuaSi PhsSi McjC p-Tol 

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Section III,B,2,d, has only limited utility for the preparation of Group IV derivatives of tetrazene. 

The purpose of this article is to summarize the preparation and properties of silyl, germyl, and stannyl derivatives of azenes N H (n = 2-5). This part II of the review deals with known Group IV derivatives of triazene, tetrazene, and pentazene (n = 3-5 excluding purely organic substituted triazenes and tetrazenes, cf. refs 2,3). Group IV derivatives of diazene were discussed in Part I of the review (1). 

Investigations on thermolysis of Group IV derivatives of trans-2-tetrazene indicate that these decompose by a free radical mechanism according to Eqs. (48) and (49) Thermolysis Pathways I and II) as well as by non-free radical pathways [Eqs. (50) and (51)] (Thermolysis Path-... 

Part I of this review deals with preparation and properties of Group IV derivatives of diazene. Part II, which appears in a forthcoming volume of Advances in Organometallic Chemistry, will cover Group IV derivatives of triazene, tetrazene, and pentazene. 

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