Thermolysis of bis(pentacoordinate) silicon compound bearing two 1-fluorodisilanyl units at 4- and 8-positions on 1,5-bis(dimethylamino)naphthalene ring: construction of disilapyrene skeleton and cyclophane-shaped siloxane dimer

The thermolysis of a bis(pentacoordinate) silicon compound having two pentacoordinate silicon units at the 4- and 8-positions on the 1,5-bis(dimethylamino)naphthalene ring in the presence of diphenylacetylene affords a 1,6-dihydro-1,6-disilapyrene derivative. This reaction might proceed through a two-site silylene trapping with two acetylene molecules accompanied by an amino group migration from the naphthyl carbon atom to the silicon atom. The dimethylamino group on each silicon atom can easily be converted into a variety of functional groups. One of the disilapyrene derivatives, bis(silanol), dimerizes by a dehydrocondensation reaction using dicyclohexylcarbodiimide to form a cyclophane-shaped molecule in 76% yield. The cyclic dimer showing a greenish yellow luminescence exhibits the UV-absorption and emission spectra characteristic of a transannular interaction between two proximal chromophores in cyclophane-shaped molecules.