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

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The 2-cyclopentadienyl-2-fluorenylpropane ligand has been converted into the monometalated derivatives M[CMe 2(C 5H 4)(C 13H 9)] (M=Li, Tl,) and CMe 2[C 5H 4(SiMe 3)](C 13H 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 5H 4)(C 13H 9)}Cl 3]. Reaction of the thallium derivative with [Ti( η 5-C 5R 5)Cl 3] afforded the ‘mixed-ring’ dicyclopentadienyl complexes [Ti{CMe 2( η 5-C 5H 4)(C 13H 9)}( η 5-C 5R 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 5H 4)(C 13H 9)} 2Cl 2]. The monocyclopentadienyl compound [Ti{CMe 2( η 5-C 5H 4)(C 13H 9)}Cl 3] was readily hydrolyzed to give [Ti{CMe 2( η 5-C 5H 4)(C 13H 9)}Cl 2] 2( μ-O) in wet acetone (0.5% H 2O). The dicyclopentadienyl derivative [Ti{CMe 2( η 5-C 5H 4)(C 13H 9)}( η 5-C 5Me 5)Cl 2] was further converted into [Ti{CMe 2( η 5-C 5H 4)(C 13H 9)}( η 5-C 5Me 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 5H 4)(C 13H 9)} 2Cl 2].