摘要：

The photolysis of phenylethynylpentamethyldisilane (1) afforded 1,1-dimethyl-2-phenyl-3-trimethylsilyl-1-silacy-clopropene (8) and 1,1-dimethyl-3-phenyl-3-trimethylsilyl-1-silapropadiene. The absorption and emission spectra of 1 were measured at 300 and 77 K. The total emission spectrum at 77 K showed the normal fluorescence from 1(π,π*) at 303 nm, the intramolecular CT fluorescence at 395 nm, and the phosphorescence from 3(π,π*) at 410.5 nm. 1,1-Dimethyl-2-phenyl-3-phenyldimethylsilyl-1-silacyclopropene (12), 1-methyl-1,2-diphenyl-3-trimethylsilyl-1-silacyclopropene (14), and 1,1,2-triphenyl-3-trimethylsilyl-1-silacyclopropene (15) have been prepared by photolysis of 1-phenylethynyl-2-phenyltetramethyl-, 1-phenylethynyl-1-phenyltetramethyl-, and 1-phenylethynyl-1,1-diphenyltrimethyldisilane, respectively. The molecular orbital calculations of ethynyl- and phenylethynyldisilane, 1-silacyclopropene, 2-silyl-1-silacyclopropene, and related compounds have been carried out. A mechanism for the formation of the silacyclopropenes is discussed on the basis of the MO calculations, emission spectra, and results of photochemical experiments.

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