| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2002: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
In this project, a silyl radical and a silyl biradical were isolated as crystals, and their structures and properties were studied.
The reduction of tris(triisopropylsilyl)chlorosilane with sodium in heptane gave tris(triisopropylsilyl)silyl radical as yellow crystals in 67% yield. The X-ray crystallographic analysis showed that the silyl radical center has a planar structure ; the sum of three Si-Si-Si bond angles around the silyl radical center is 359.99°. In heptane, this silyl radical has the half-life of 4 days at room temperature, while in a heptane solution containing aromatic hydrocarbons such as fluorene, naphthalene, etc., its half-life is 1.5-3 months. These facts indicate that this silyl radical is stabilized by the interaction with aromatic hydrocarbons.
The reduction of trans-1,3-dibromo-1,2,2,3,4,4-hexa-tert-butylcyclotetrasilane with potassium in benzene gave (trans-1,2,2,3,4,4-hexa-tert-butyl-1,3-cyclotetrasilanediyl)dipotassium via three kinds of paramagnetic intermediates. The third paramagnetic species showed a doublet with satellites in the ESR spectrum and was isolated as red crystals. The X-ray crystallographic analysis showed that this species is 1,2,2,3,4,4-hexa-tert-butyl-1,3-cyclotetrasilanediyl biradical. The silyl radical centers have a planar structure. The distance between two silyl radical center is 2.796(3)Å, and a covalent bond is not formed between them. This is the first example of the observation of a silyl biradical by ESR and the isolation of a silyl biradical as crystals.
The final product of this reduction, (trans-1,2,2,3,4,4-hexa-tert-butyl-1,3-cyclotetrasilanediyl)dipotassium, was isolated as purple crystals. The X-ray crystallographic analysis showed that the silyl dianion forms a novel 1-D supramolecular structure, in which the silyl dianion interacts with benzene.
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