Measurement of the 29Si central atom couplings in silicon-centred radicals with phenyl substituents
- 1 January 1992
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 9,p. 1475-1480
- https://doi.org/10.1039/p29920001475
Abstract
Following γ-irradiation of the completely deuteriated silicon compounds C6D5SiD3, (C6D5)2SiD2 and (C6D5)3SiD at 77 K, features were detected by EPR spectroscopy from the 29Si satellite transitions of the corresponding silicon-centred radicals, derived from Si–D bond cleavage. Thus the anisotropic 29Si hyperfine tensors could be fully evaluated, leading to the conclusion that these are still pyramidal species, but are partially delocalised, rising to a maximum of ca. 30% spin transfer to the phenyl groups in the triphenylsilyl radical. The chloro-analogues, C6D5SiCl2˙ and (C6D5)2SiCl˙, were also studied, following γ-radiolysis of C6D5SiCl3 and (C6D5)2SiCl2 at 77 K, the latter giving rise to both these radicals and indicating a radiolytic mechanism involving both Si–C and Si–Cl bond cleavage. In order to provide ‘base’ values for couplings in related species without phenyl substituents, the radicals MeSiCl2˙ and HSiCl2˙ were also studied as formed by the radiolysis of MeSiCl3 and HSiCl3.Keywords
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