Tetrakis hydrazine, formation

Interaction of anhydrous hydrazine and titanium isopropoxide is explosive at 130° C in absence of solvent. Evaporation of solvent ether from the reaction product of tetrakis(dimethylamino)titanium and anhydrous hydrazine caused an explosion, attributed to formation and ignition of dimethylamine. /V-Metal derivatives may also have been formed. 

The formation of the silylhydrazines depends on the reactivity and the bulkiness of the halosilanes. The condensation increases with increasing number of the hydrogen atoms. While iodosilane or bromo(methyl)-silane yield the tetrakis(silyl)hydrazines,912... 

Compound 126 crystallizes in a chair conformation. Because of the inversion center, the atoms N2, Sil, N2a, and Sila lie exactly in one plane. The atoms N1 and Nla are 47 pm above and below this plane, respectively. The sum of angles at N2 amounts to 359.8°. This nitrogen atom, in contrast to the NH-functional N1 with 349.9, is. vp2-hybridized. The angle Si2-N2-Sil of 140.7 is comparatively increased. The average Si—N and N—N bond distances are 175 and 148 pm, close to the expected values of 174 pm for Si—N and 145 pm for N—N.60 The same method of preparation, shown in Eq. (39), led to the formation of the first fluorosilyl functional hydrazine six-membered rings 127 and 128.43 The dilithiated bis(silyl)hydrazines 10 and 12 react with tetrafluorosilane to yield tetrakis-(silyl)hydrazines, which again react with the lithium derivatives. 

Summary Mono(silyl)hydrazines condense to bis(silyl)hydrazines at higher temperature. The degree of oligomerization of mono- and dilithiated silylhydrazines in the crystal depends on the bulkiness of the substituents. Reactions of lithiated silylhydrazines with fluorosilanes lead, for example, to the formation of tetrakis(silyl)-hydrazines, six-, four- and five-membered rings. Formaldehyde derivatives of mono-(silyl)hydrazones are obtained in a reaction of mono(silyl)hydrazines with aqueous formaldehyde solution. 0-Silylpyrazolones can be synthesized by treating mono(silyl)-hydrazines with acetoacetic ester. A dipyrazolonesilane is formed in the reaction of an O-silylpyrazolone with dichlorodimethylsilane. 

Alkyl radicals are conveniently generated by photodecomposition of azoalkanes. A kinetic study of the rearrangement of cyclopropyl radicals (1), obtained by photolysis of the azoalkanes (2), has been described. Particularly high radical concentrations leading to a dramatic change in the product ratio of tetrakis(pentafluoro-ethyl)hydrazine and perfluorobutane have been achieved in the pulsed laser excitation of perfluoroazoethane. On photolysis, azosulphonates also function as radical traps, with the formation of hydrazyl radicals as reactive intermediates. ... 

Summary Condensation of stable mono(silyl)hydrazines leads to the formation of bis(silyl)hydrazines above 200°C. The degree of oligomerization of mono- and dilithiated silylhydrazines depends on the bulkiness of the substituents. Lithiated silylhydrazines react with fluorosilanes forming, for example, tris- and tetrakis(silyl)hydrazines, and six-membered rings. In oxidation reactions of bulky bis(silyl)hydrazines bis(silyl)diazenes are obtained. Lithiumderivatives of fluoro functional bis(silyl)hydrazones are precursors for l,2-diaza-3-sila-5-cyclopentenes. Further lithiation with iBuLi leads to tricyclic compounds and LiF. 

Isomerism is observed in the formation of tetrakis(silyl)hydrazines. The reaction of dilithiated bis(dimethylphenylsilyl)hydrazine with two equivalents of trifluoromethylsilane leads to the formation of the isomeric products 7 and 8 (Eq. 6) [2],... 

Alternatively, under strong reductive conditions, e.g. electrochemical reduction, arylpalladium(II) halide (XIII) is reduced to arylpalladium(0) which, upon the second oxidative addition, gives diarylpalladium(II) complex, also capable of undergoing reductive elimination of biaryl similarly to XIV [10]. Isopropanol [50-52], amines [4,17,52-54], hydrazine [55], tetrakis(dimethylamino)ethylene [18], hydroquinone [56], tetrabutylammonium ftuoride [57], formates [58-60], zinc [61-64], and molecular hydrogen [65] have been used as stoichiometric reductants. Electro-reductive homocoupling of aryl halides was also reported [10]. The most important methods for... 

Silylhydrazines condense very easily. The tendency to condense depends on the buUdness of the substituent. For example the condensation product of tert-butyldimethylsilylhydrazine can be isolated as the mono-, the trimethylsilylhydrazine as the his-, and the dimethylsilylhydrazine as the tris(silyl)hydrazine, and the methylsilylhydrazine condenses with formation of the tetrakis(silyl)hydrazine (MeaCSiMejNH-NHj, MeaSiNH-NHSiMej, (Me2HSi)2NNHSiHMe2, (MeH2Si)2N-N(SiH2Me)2, respectively). 

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