(Fluorosilyl)ethylenediamines and fluorosilyl-1,3-diaza-2-silacyclopentanes

Abstract

This paper presents the chemistry of ethylenediamines and fluorosilanes. The synthesis of thermally stable monosilyl ( 1– 5)- and bis(fluorosilyl)ethylenediamines ( 6) is described. Starting with the dilithium salt of ethylenediamine and F 2Si(CMe 3) 2 the five-membered 1,3-diaza-2-silacyclopentane ( 8) is obtained. The reaction of tetra- and trifluorosilanes with dilithiated bis(silyl)ethylenediamines leads to the formation of 1,3-diaza-2-fluorosilylsilacyclopentanes ( 9– 14). Fluorosilanes substitute 8 in 1 and 3 positions ( 15– 28). A fluorosilyl-bridged five-membered ring ( 29) is isolated in the reaction of 1-trimethylsilyl-1,3-diaza-2-silacyclopentane, BuLi and MeSiF 3. In the synthesis of N-fluorosilyl-1,3-diaza-2-silacyclopentanes constitutional isomers were formed ( 30–33). Quantum-chemical calculations support the isomerisation mechanism. An iminosilane with an SiN double bond is the intermediate product of the rearrangement process. Crystal structures of 7, 13, 20 and 23 are reported.