Aminofluorenyl-pentamethylcyclopentadienyl and bis(aminofluorenyl) derivatives of group 4 metals

New group 4 compounds containing a 9-(dialkylamino)fluorenyl ligand have be en prepared, and their properties-and reactivities have been briefly invest igated. Single-crystal X-ray analysis of {9-(N,N-dimethylamino)fluorenyl}(2 )ZrCl2 (4) reveals strong zirconium-nitrogen dative bonds. The asymmetric u nit contains two molecules with an unusual coordination of aminofluorenyl l igands, best described as comprised of a strong Zr-N dative interaction and essentially an eta (1)-fluorenyl coordination, supplemented by a weak addi tional C=C dative interaction of one double bond of one of the benzo units. The barrier to rotation around the C-N bond of {9-(N,N-diisopropylamino)fl uorenyl}(pentamethylcyclopentadienyl)ZrCl2 (9) has been determined: DeltaG( double dagger)(-25 degreesC) = 11.1 kcal.mol(-1). Unlike related aminoborol lide complexes, aminofluorenyl complexes resist quaternization by alkyl hal ides. Several aminofluorenyl complexes have been tested for propylene polym erization behavior in the presence of methylaluminoxane (MAO); atactic poly propylene is obtained with very low activities. The syntheses of 9-(dialkyl amino)fluorene compounds are described, as are the syntheses of group 4 com pounds via the corresponding 9-(dialkylamino)fluorenide lithium salts.