Dialkylamino-bis(trimethylsilyl)amino-chlorborane und ihre Reaktion mit Natrium-bis(trimethylsilyl)amid

Zusammenfassung Verbindungen des Typs R₂NBCIN(Sime ₃)₂ ^* (R=C₂H₅,ⁱC₃H₇, C₆H₁₁, C₆H₅) bleiben bis zu hohen Temperaturen beständig. Sie reagieren jedoch mit NaN(Sime ₃)₂ unter Übertragung einer Methylgruppe von einem Silicium-zu einem Boratom zu N,N-Bis(trimethylsilyl)-tetramethylcyclodisildiazan und R₂NBmeN(Sime ₃) (R=C₂H₅,ⁱC₃H₇).

---

Compounds of the type R₂NBClN(Sime ₃)₂ ^* were prepared. (R=C₂H₅,ⁱC₃H₇, C₆H₁₁, C₆H₅. They do not show any tendency to condense thermally under elimination of trimethylchlorosilane. When these silylaminoboranes were allowed to react with NaN(Sime ₃)₂, complicated rearrangements were observed. The compounds in which R=C₂H₅ orⁱC₃H₇ rearranged under formation of N,N-bis(trimethylsilyl)-tetramethylcyclodisildiazane and R₂NBmeN(Sime)₂. In this reaction a migration of a methyl group from silicon to boron occurs.

     

Bis (trimethylsilyl) thioketone

Tris (trimethylsilyl) methylsulphenylbromide undergoes facile Me₃ SiBr elimination to give bis (trimethylsilyl) thioketone.     

Tetrakis(trimethylsilyl)tetrahedrane

Tetrakis(trimethylsilyl)tetrahedrane 3 has been synthesized upon irradiation of tetrakis(trimethylsilyl)cyclobutadiene 8, which can be prepared either by thermal nitrogen elimination from trimethylsilyl[1,2,3-tris(trimethylsilyl)-2-cycloprop-1-enyl]diazomethane 7 or by mild oxidation of cyclobutadiene dianion 9 with 1,2-dibromoethane. The structural characterization of tetrahedrane 3 has been achieved by X-ray crystallography. The surprising thermal stability of 3 - which is stable up to 300 degrees C - is discussed.     

Einkristallstrukturanalyse vonBis(trimethylsilyl)peroxid

Zusammenfassung Bis(trimethylsilyl)peroxid wurde aus Trimethylchlorsilan, Wasserstoffperoxid und 1,4-Diazobicyclo[2.2.2]octan dargestellt. Ein Einkristall wurdein situ auf einem Vierkreisdiffraktometer gezüchtet und mittels Einkristallstrukturanalyse charakterisiert (T=193(2) K, 2522 Reflexe, P2₁/c;a=606.7(1) pm,b=1098.5(1) pm,c=858.2(1) pm, =101.88(2)°,Z=2,R=0.045). Die Konformation des Moleküls im Kristall ist durch C-H...O-Brücken bestimmt.

---

Crystal structure ofbis(trimethylsilyl)peroxide

Summary Bis(trimethylsilyl)peroxide has been prepared from trimethylchlorsilane, hydrogen peroxide, and 1,4-diazobicyclo[2.2.2]octane. Crystal growth was achievedin situ on a diffractometer and characterized by crystal structure analysis (T=193(2) K, 2522 reflections, P2₁/c;a=606.7(1) pm,b=1098.5(1) pm,c=858.2(1) pm, =101.88(2)°,Z=2,R=0.045). The molecule's conformation in the crystalline solid is determined by C-H...O-bridges.

     

The mass spectra of some tris(trimethylsilyl)acylsilanes and tris(trimethylsilyl)silanes

While tris(trimethylsilyl) alkanoylsilanes fragment in the acylsilane form yielding [(Me₃Si)₃SiCO]⁺ by α-cleavage, the molecular ions of their aryl counterparts rearrange to ionized silaethenes prior to cleavage, paralleling known photochemical behaviour. Sila-allyl type structures are attributed to the stable [M? Me˙]⁺ ions obtained by subsequent cleavage. Metastable ion characteristics reveal the identity of the structures of the monomeric silaethene ions obtained from one of the aroylsilanes and a 1,2-disilacyclobutane. The non-compliance of the alkanoylsilanes with their photochemical behaviour is attributed to a preferred elimination of the stable alkyl radical (R˙) from the molecular ions. Several polysilanes display abundant odd-electron ions which may possess a disilene structure.     

Elimination of bis(trimethylsilyl)stannylene from tris(trimethylsilyl)stannylated zirconocene and hafnocene chlorides

Reactions of (Me₃Si)₃SnK with Cp₂MCl₂ (M = Zr, Hf) give the respective stannylated metallocene chlorides. These complexes display a tendency to eliminate bis(trimethylsilyl)-stannylene under Cp₂M(Cl)SiMe₃ formation.