The reactions of silicon difluoride with sulfur compounds: the silicon-sulfur bond
Williams, Dennis Lee
Margrave, John L.
Master of Arts
The reactions of silicon difluoride with several sulfur containing compounds have been investigated in an attempt to synthesize compounds containing the silicon-sulfur bond. Of the previous reactions of silicon difluoride with sulfur compounds, only two, the hydrogen sulfide and sulfur reactions, produced compounds containing silicon-sulfur bonds. The products of the H2S reaction were SiF2HSH, Si2F4HSH, SiF2HSSH and Si2F4HSSH. The reaction between SiF2 and sulfur produced both linear and cyclic fluorosilthianes. SiF2 abstracted the oxygen atom from thionyl fluoride and the chloride to form linear and cyclic halosiloxanes. SF4, SF6 and thiophene apparently did not react. The first new reaction of SiF2 was with dimethylsulfoxide. As in the thionyl fluoride reaction, oxygen abstraction seemed to be the favorable reaction due to the production of Si20F6 and (CH3)2S. A small amount of CH3SiF3 was also produced. Dimethyl sulfide is rather unreactive towards SiF2 as only a small amount of CH3SiF3 was formed in their reaction. Oxygen abstraction and polymer formation were evidenced in the reaction of dimethyl sulfite with SiF2. A large amount of Si20F6 and a surprisingly stable polymer were formed. The polymer was not pyrophoric or hydrolysis sensitive as are most SiF2 polymers. The existence of (-C-O-Si-) linkages in the polymer was implied by the cracking of CH30SiF3 from the polymer matrix. There was no apparent reaction between bis- (trifluoromethyl) disulfide and SiF2. Ethylene sulfide, methane sulfonyl chloride and dimethyl disulfide reacted with SiF2, but the reaction products are not fully characterized. The scarcity of silicon-sulfur compounds in the reaction products is undoubtedly due to the instability of these compounds and to the affinity of SiF2 for atoms other than sulfur. It may be possible to produce compounds of this sort by reacting SiF2 with thiocarbonyl compounds and sulfur monohalides or by reacting gaseous SiS or SiS2 with various reagents.