Regioselective formation of[2-(η5-cyclopentadienyl)-2-fluorenylpropane]-titanium complexes:precursors, synthesis, structure and reactivity

Abstract The 2-cyclopentadienyl-2-fluorenylpropane ligand has been converted into the monometalated derivatives M[CMe 2 (C 5 H 4 )(C 13 H 9 )] (M=Li, Tl,) and CMe 2 [C 5 H 4 (SiMe 3 )](C 13 H 9 ). These alkylating reagents have been characterized, and used to synthesize a new series of organotitanium (IV) complexes. The trimethylsilyl derivative was treated with TiCl 4 to give the monocyclopentadienyl compound [Ti{CMe 2 ( η 5 -C 5 H 4 )(C 13 H 9 )}Cl 3 ]. Reaction of the thallium derivative with [Ti( η 5 -C 5 R 5 )Cl 3 ] afforded the ‘mixed-ring’ dicyclopentadienyl complexes [Ti{CMe 2 ( η 5 -C 5 H 4 )(C 13 H 9 )}( η 5 -C 5 R 5 )Cl 2 ] (R=H, Me), whereas the reaction of TiCl 4 with two equivalents of the lithium compound led to the dicyclopentadienyl complex [Ti{CMe 2 ( η 5 -C 5 H 4 )(C 13 H 9 )} 2 Cl 2 ]. The monocyclopentadienyl compound [Ti{CMe 2 ( η 5 -C 5 H 4 )(C 13 H 9 )}Cl 3 ] was readily hydrolyzed to give [Ti{CMe 2 ( η 5 -C 5 H 4 )(C 13 H 9 )}Cl 2 ] 2 ( μ -O) in wet acetone (0.5% H 2 O). The dicyclopentadienyl derivative [Ti{CMe 2 ( η 5 -C 5 H 4 )(C 13 H 9 )}( η 5 -C 5 Me 5 )Cl 2 ] was further converted into [Ti{CMe 2 ( η 5 -C 5 H 4 )(C 13 H 9 )}( η 5 -C 5 Me 5 )Me 2 ] by alkylation with LiMe. Structural data of the titanium complexes demonstrate the η 5 -coordination of the cyclopentadienyl ring of the ancillary ligand, whereas the fluorenyl ring is not coordinated to the metal center. This mode of coordination is confirmed by the X-ray crystal structure analysis of [Ti{CMe 2 ( η 5 -C 5 H 4 )(C 13 H 9 )} 2 Cl 2 ].