Photochemical transformation of a cyclic polysilane to a cyclic carbosilane via (η5-C5H5)Fe(CO)2)CH2, FpCH2, substitution

The complex FpCH2-c-Si5Me9 (1), Fp=(η5-C5H5)Fe(CO)2, was synthesized by the salt-elimination reaction between [Fp]−Na+ and ClCH2-c-Si5Me9. The complex is stable indefinitely at RT, but highly reactive toward UV irradiation to yield the rearranged product FpSi(SiMe3)(c-SiMe2CH2(SiMe2)3) (2) in which the initial exo-cyclic methylene group has been incorporated into a 5-membered ring and an initial ring Me2Si group becomes an exo-cylic Me3Si group. The structure of 2 was confirmed by single-crystal X-ray diffraction.