Аннотация:
1-Silacyclopenta-2,4-diene 1 has been generated by vacuum pyrolysis of 5-silaspiro[4.4]nona-2,7-diene 5 and by photolysis of matrix-isolated 1,1-diazido-1-silacyclopent-3-ene 6, and characterized by matrix-isolation IR and UV spectroscopy; reversible interconversion of 1 with 1-silacyclopenta-1,3-diene 2, 1-silacyclopenta-1,4-diene 3 and 1-silacyclopent-3-ene-1,1-diyl 4 has been observed upon irradiation at various wavelengths; the red-shifted UV absorption of 2 and 3, together with their low Si=C stretching frequencies, provide evidence for Si=C—C=C π conjugation.