Conjugated polymers are prominent semiconductors that have unique electric conductivity and photoluminescence. Synthesis of conjugated polymers under high pressure is extremely appealing because it does not require a catalyst or solvent used in conventional chemical methods. Transformation of acetylene and many of its derivatives to conjugated polymers using high pressure has been successfully achieved, but not with dimethyl acetylene (DMA). In this work, we present a high-pressure study on solid DMA using a diamond anvil cell up to 24.4 GPa at room temperature characterized by in situ Fourier transform infrared and Raman spectroscopy. Our results show that solid DMA exists in a phase II crystal structure and is stable up to 12 GPa. Above this pressure, amorphization was initiated and the process was completed at 24.4 GPa. The expected polymeric transformation was not evident upon compression, but only observed upon decompression from a threshold compression pressure (e.g. 14.4 GPa). In situ florescence measurements suggest excimer formation via crystal defects, which induces the chemical reactions. The vibrational spectral analysis suggests the products contain the amorphous poly(DMA) and possibly additional amorphous hydrogenated carbon material.

The heats of formation for a series of disilenes and the corresponding silylenes have been calculated by using the MOBI method. Substitution by methyl groups and chlorine atoms was included and, with one exception, it is found that the disilene ABSi=SiXY is more stable than the corresponding silylene. Trends in stability with substitution are established. The isomers of SiCH4 were studied and it is found that H2Si=CH2 and CH3SiH are similar in energy, while SiH3CH is considerably less stable than either. A study is made of the singlet-triplet separations for MeSiH and SiH3SiH. The former is found to be 78.0 kJ mol"1 and the latter 39 kJ mol"1, the lowest energy state being the singlet.