Savage, William John

2019-02-15T14:20:06Z

2019-02-15T14:20:06Z

1975

Two attempts to módify the ammonium salts of silyl thiol and silyl selenol were made in an effort to make them easily soluble. Both attempts were unsuccessful. The first was to try to form the potassium salt by using an ion exchange resin; the second was to prepare the methylsilyl derivative in the hope that it would be soluble. The ammonium salt of silyl tellurol was also prepared by an analogous route to the sulphur and selenium compounds.

2H₂Te + (SiH₃)₃N → NH₄TeSiH₃ + (SiH3)₃Te ¹.

Methyl silyl telluride was prepared from it by adding methyl iodide.

CH₃I + NH₄ TeSiH₃ → CH₃TeSiH₃ + NH₄ I ².

Lithium silyl oxide, sulphide and selenide was prepared by the reaction of methyl lithium, as a solution in diethyl ether at -64°, with disiloxane, disilyl sulphide and disilyl selenide.

CH₃Li + (SiH₃)₂Y → LiYSiH₃ + CH₃SiH₃ ³.

Y = (0, S, Se)

Similar reactions were carried out with methyl lithium and trisilyl phosphine and trisilyl arsine.

CH₃Li + (SiH₃)₃Z→LiZ(SiH₃)₂ + CH₃SiH₃'⁴

Z= (P, As)

Yields of the lithium derivatives were all of the order of 80% and they were characterised by i.r., raman and n.m.r. spectroscopy. In some cases a reaction with trimethylsilyl chloride was also carried out.

Reactions of these compounds, as a solution in diethyl ether, were carried out with a variety of reagents but most were unsuccessful in that the desired products were not isolated. Instead, the main volatile silyl product was generally (SiH₃)₃Z or (SiH₃)₂Y. This was attributed to the side-reactions:

SiH₃ - Y - Q +Bθ → SiH₃B + θY - Q ⁵.

and (SiH₃)₂Z - Q + Bθ → SiH₃B + SiH₃QZθ ⁶.

where Q is any group of interest

and Bθ is a base - in this case YSiH₃ or Z(SiH₃)₂

This conclusion was confirmed by reactions of the silyl anions and closely related molecules producing exchange situations. Attempts to limit the extent of reactions (5) and (6) consisted of the use of benzene as a solvent, the use of trimethylamine and the absence of solvent. The first two were unsuccessful but the latter worked. It was possible to prepare disilyl phosphine and 1,1,1-trimethyl disiloxane by this method.

2LiP(SiH₃)₂ + H₂S -- HP(SiH₃)₂ + Li₂S ⁷.

Li0SiH₃ + (CH₃)₃SiCl → (CH₃)₃0SiH₃ + LiCl ⁸.

http://hdl.handle.net/1842/33827

The University of Edinburgh

Annexe Thesis Digitisation Project 2019 Block 22

Some silyl anions

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy