Methyl-silylene

Platinum-catalyzed hydrosilylation is applicable for the crosslinking of copoly(methyl-silylene/l,4-phenylene/methylvinylsilylene), yielding a thermoset material293. 

Poly(oxycarbonyl-2,4-hexadiyne-1,6-diyl), see Poly(2,4-hexadiyne-1,6-ylene carbonate), 2665 Poly[oxy(methyl)silylene], 0483 Poly(l -pentafluorothio-1,2-butadiyne), 1375... 

This pattern seems to be fairly common for main group compounds. In Table 2, results with the same range of functionals are shown for the singlet-triplet splitting in methyl-silylene [24]. In this system, the unpaired electrons reside on a different atom (Si versus C), and the singlet is now the... 

See Poly [oxy (methyl)silylene] l-Allyloxy-2,3-epoxypropane See other ALLYL compounds, i,2-epoxides... 

Figure 1. A. Absorption spectra of poly(n-hexyl methyl silylene) at four temperatures...

Figure 3 shows a plot of the fluorescence maximum for poly(n-propyl methyl silylene) in hexane vs. sin ir/2(N + 1) using a defect energy of 1650 calories/mole. Although the ag eement here seems good, the uncertainty in location of the fluorescence maximum is large as the band broadens near room temperature and may disguise a real nonlinearity. Nevertheless, this result lends credibility to the rotational isomeric state model for thermochromism in these polysilylenes. 

Figure 2. Thermal activation of chain defects in poly(n-propyl methyl silylene).

Figure 8 is the phosphorescence spectrum taken from a glassy solution of poly(n-propyl methyl silylene) in methyl cyclopentane at 89°K. This emission is similar in width to the film emission, as are the solution spectra of the other polymers. Again delayed fluorescence is evident but the sharp vibrational fine structure is lost. The solution and film spectra are not expected to be comparable since they represent conformational equilibria (at room temperature for film and the Tg of 3-methylpentane for the solutions). 

The fluorescence of the phenyl polymer is similar in shape to the fluorescence from the alkyl polymers and the similar shape of the phosphorescence spectrum, as well, suggests that the origins of the electronic spectrum are also much the same. The apparent increased quantum yield for phosphorescence in poly(phenyl methyl silylene) probably reflects a mixing of the ring electronic levels with the levels of the chain. Both the fluorescence and phosphorescence of the naphthyl derivative are substantially altered relative to the phenyl polymer. Fluorescence resembles that of poly(B Vinyl naphthalene) (17,29) which is attributed to excimer emission. Phosphorescence is similar to naphthalene itself. These observations suggest that the replacement of an alkyl with phenyl moiety does not change the basic nature of the electronic state but may incorporate some ir character. Upon a naphthyl substitution both the fluorescence and phosphorescence become primarily tt-tt like. 

Another report of a silene-to-silylene rearrangement involves a 1,2-shift of a trimethylsilyl group, converting l-(trimethylsilyl)- 1-methylsilene into methyl[(tri-methylsilyl)methyl]silylene (equation 96)207. 

Fig. 2.3 Quantum yield for charge carrier generation as a function of the electric field strength determined at 295 K for three poly-silylenes poly(biphenyl methyl silylene),...

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