The synthesis and structural characterization of silyl-substituted fluorenes

Three silyl-substituted fluorenes have been prepared by direct synthetic methods and structurally characterized by X-ray diffraction. The three silyl-substituted fluorenes studied were 9-trimethylsilylfluorene (1), 9-(tert-butyldimethyl) silylfluorene (2), and 2,7-di-tert- butyl-9- trimethylsilylfluorene (3). Complex 1 is orthorhombic, P2(1)2(1)2(1), a = 6.2681(14) Angstrom, b = 14.329(3) Angstrom, c = 15.231(4) Angstrom, Z = 4. Complex 2 is monoclinic, P2(1)/c, a = 12.1953(10) Angstrom, b = 6.9977( 6) Angstrom, c = 19.6536(17) Angstrom, beta = 93.818(2) degrees, Z = 4. Complex 3 is monoclinic, P2(1)/c, a = 11.9954( 9) Angstrom, b = 9.8978( 7) Angstrom, c = 18.5464(13) Angstrom, beta = 92.456(2) degrees, Z = 4. The long carbon-silicon bonds effectively remove any significant intramolecular interactions as little distortion is exhibited around the sp(3)-carbon atom and the fluorenyl backbone demonstrates near planarity. The bulky silicon substituents also prevent intermolecular interactions, as only a few close contacts less than 4.0 Angstrom exist in all three solid state structures.