Neue mono-und spirobicyclische Aminosilane: Synthese, Struktur und Eigenschaften / New Mono-and Spirobicyclic Aminosilanes: Synthesis, Structure and Properties

Abstract

The reactions of the N.N'-dialkyl/aryl-ethylenediamines l a - e with equimolar amounts of tetrachlorosilane give the monocyclic aminosilanes 2 a - e in good yields. With two equivalents of the diamines 1 only one spirobicyclic compound, l,4,6,9-tetrabenzyl-l,4,6,9-tetraaza-5-silaspiro[ 4.4]nonane, 4e, can be prepared. It is only via an independent double deprotonation of the diamines that the spirobicyclic ethyl- and isopropyl derivatives 4a and 4b are also becoming available. A ll compounds have been characterized by multi-NMR and mass spectrometry. In three cases (2d, 2e and 4e), the crystal and molecular structures have been determined by X-ray diffraction analysis. A planar silaimidazolidine ring system has been confirmed for the phenyl substituted species 2d, while in the corresponding benzyl substituted homologue 2 e both nitrogen atoms are pyramidal and lead to ring puckering. The silicon atom in 4 e shows a strongly distorted tetrahedral coordination. The endocyclic angle N 1 - Si - N2 = 92.8(1)° is nearly orthogonal, and the angle between the planes defined by the silicon and the two nitrogen atoms of the five-membered rings is 81.4(1)°.