Poly- und spirocyclische Silylhydrazone – Synthese und Molekülstrukturen

Poly- and Spirocyclic Silylhydrazones — Synthesis and Molecular Structures Bulky aminotrifluorosilanes react with lithiated dimethylketone-hydrazone to give 1,2-diaza-3-sila-5-cyclopentenes — DSCP — ( 1, 2 ). The 4-silylated ( 3–5, 8–15 ) and siloxysilyl-substituted ( 17, 18 ) rings eliminate no halosilane or siloxane thermally. Lithiated 2 dimerises with LiF elimination to give the (2+2)cycloadduct of a 1,2-diaza-3-sila-3,5-cyclopentadiene ( 6 ). Lithiated DSCP reacts with MeSiF₂N(CMe₃)SiMe₂CMe₃ via a nucleophilic 1,3-methanide ion migration to form LiF and the spirocyclic compound 18 . A compound with spirocyclic silicon ( 21 ) is formed in the reaction of bis(1,2-diaza-3-sila-5-cyclopenten-4-yl)difluorosilane ( 19 ) and the lithium salt of dimethyl-ketone-tert-butylhydrazone. The crystal structures of 6 and 21 are reported.     

Neue Moleküle A4B3 im System P4Se3–As4Se3

Novel A₄B₃ Molecules in the System P₄Se₃–As₄Se₃ By means of ³¹P-NMR and masspectroscopic measurements in the system P₄Se₃–As₄Se₃ was shown that in the melt and vapour phase at all compositions molecules of the type P_{4 ? n}As_nSe₃ are formed. A separation was possible by liquid chromatography (RP 18-column). The concentration distribution of the different species is nearly statistical. In the solid state at ambient temperature regions of solid solubility with α-P₄Se₃, α⁺-phase, α-P₄S₃ and α-As₄Se₃ structure were observed. P₃AsSe₃ could be transformed into a plastically-crystalline phase with β-P₄S₃ structure. At higher temperatures the phase decomposes slowly. The thermal behaviour of PAs₃Se₃ is strongly influenced by the heating rate. Using low heating rates it decomposes into an amorphous phase, by fast heating a transformation into a metastable plastically-crystalline modification was achieved. During long extraction with CS₂ molecules P_{4 ? n}As_nS_{3 ? m}Se_m are formed by an exchange reaction. They can also be prepared by melting the proper amounts of the elements.