Silyl-mediated coordination of functionalized fluorenyl ligands

The use of silylated ligands such as [RC5H4(CH2)2OSiMe3 R=H, SiMe3] constitutes an efficient method to generate p-coordination and/or metal-alkoxy complexes [Firenze]. Upon the favoured release of Me3SiCl, [1] the silyl-mediated synthesis is an efficient strategy to afford nucleophilic additions under milder condition. The silyl-fluorenide [SiMe3Flu-, Flu=C13H8] with propylene oxide causes prompt O-silyl migration to give [Flu(CH2CH(Me)OSiMe3]- to obtain (scheme1): A) p- Rh-coordination. B) Monohapto s-1Flu(CH2CHMeOSiMe3)TiCl3(THF)2 1, which forms h5- Flu(CH2CHMeOSiMe3)TiCl3 2 under thermal treatment. C) Siloxy-silyl Fluorene derivative, which can be viewed as a synthone of the corresponding dianion. With the aim of extending the chemistry of Cp- alkoxide Ti complexes [2] to p--extended ligands, we explored the reaction of TiCpCl3 with Flu derivatives bearing alcohol- or siloxy-moieties [C13H9(CH2CH(Me)OR)] [R=H FluOH a; R=SiMe3 FluOSi b]. Both a and b give rise to new alkoxy-Ti species FluOTiCpCl2 3, via releasing of [HPy]Cl (scheme 2). X-ray structures of a and 3 will be reported. [1] Trouvé G.; Laske D.A.; Meetsma A.; Teuben J.H. J. Organomet. Chem. 1996, 511, 255; Christie S.D.R.; Man K.W.; Whitby R.J.; Slawin, A.M.Z, Organomet. 1999, 18, 348 [2] Turner L.E., Thorn M.G., Swartz R.D., Chesnut R.W., Fanwick P.E., Rothwell I.P., Dalton Trans., 2003, 4580.