Synthesis, structure and photoluminescence of 1,2-disila-acenaphthene Si₂C₁₀H₁₀ and 1,2-diaryldisilane reference compounds

For the synthesis of the diaryldisilanes Ar-SiH₂SiH₂-Ar (la, Ar = phenyl; Ib, Ar = p-tolyl; le, Ar = mesityl; Id, Ar = p-anisyl) two convenient preparative routes are reported. The crystal structures of le and Id have been determined in Xray diffraction studies; the disilanes have a staggered transconformation with a crystallographically imposed center of inversion. For la-d no photoluminescence phenomena can be observed. 1,2-Disila-acenaphthene (2) is synthesized in acceptable yield by treatment of 1,8-dilithionaphthalene with 1 equivalent of l,2-bis[((trifluoromethyl)sulfonyl)oxy]disilane Tf-SiH₂SiH₂-Tf. The crystal structure of 2 has also been determined by X-ray diffraction. The molecule has no crystallographically imposed symmetry but closely follows the symmetry elements of point group C_2v. Solutions of 2 exhibit intense fluorescence in the near UV region at room temperature. The fluorescence spectra are discussed in comparison with data on acenaphthene and naphthalene.