Silaanthracenes matrix isolation

Evidence for the formation of 34 (R = Ph) was provided by neutralization reionization mass spectrometry and more directly by the matrix isolation and spectroscopic investigations on 34 (R = Ph) in an argon matrix at 12 K. The UV spectrum of 34 (R = Ph) exhibits characteristic bands at X = 364, 386, 404, 420, 440, 470 and 502 nm, resembling those of the electronic spectrum of anthracene, but with the expected bathochromic shifts. If one irradiates into the maximum at X = 502 nm, all bands shown in the spectrum disappear completely within 5 minutes. The vanishing of these characteristic bands can again be explained by the photoisomerization of silaanthracene 34 (R = Ph) to the corresponding Dewar valence isomer. 

Markel and Schlosser reported the synthesis of the substituted silabenzene 3 which was stable in solution up to 170 K . Kinetic stabilization by bulky substituents led to the isolation in an argon matrix of 9, R = MesSi or -PrMe2Si by Jutzi, Maier and coworkers 9, R = -PrMe2Si was stable up to 90 K even without an argon cage . In 1991 Maia-and coworkers isolated and characterized spectroscopically in the gas phase and in an argon matrix at 12 K the 9-silaanthracenes, 10, R = H, Ph . Most recently, Okazaki and coworkers reported the synthesis and isolation of 2-silanaphthalene (1), the first silaben-zenoid compound which is a stable crystalline material even at room temperature. ... 

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