Reactions of organotitanoxane fluorides with AlR3 (R = Me, Et, CH2Ph) and Me3SiCl: X-ray crystal structures of [C5Me5Ti(mu-O)](4)F[mu-F)AlMe3](3), [C5Me5Ti(mu-O)](4)F-3[mu-F)Al(CH2Ph)(3)], [C5Me5Ti(mu-O)Et](4), and (C5Me5)(4)Ti4O5X2 (X = Cl and F)

摘要

A new pentamethylcyclopentadienyl titanoxane fluoride (C5Me5)(4)Ti4O5F2 (1b) has been synthesized from (C5Me5)(4)Ti4O5Cl2 using the fluorinating reagent Me3SnF. The fluorination of organotitanoxane chlorides proceeds via a proposed intermediate similar to the four-membered ring Ti(mu-Cl)(mu-F)Sn and the bridged Ti(mu-F)ClSnMe3 species. The reactions of 1b and [C5Me5Ti(mu-O)F](4) with AlR3 (R = Me, Et, CH2Ph) afforded the thermally unstable adducts [C5Me5Ti(mu-O)](4)F4-n[(mu-F)AlR3](n) (n = 1-4), which proceed with selective exchange of fluorine atoms for alkyl groups to give an eight-membered alkylated ring compound [C5Me5Ti(mu-O)R](4). The reactions of 1b and [C5Me5TiO(mu-O)F](4) with Me3SiCl result in exchange of fluorine for chlorine atoms. Moreover, using an excess of Me3SiCl leads to a novel oxygen-chlorine exchange reaction to give C5Me5TiCl3. The crystal structures of complexes (C5Me5)(4)Ti4O5X2 (X = Cl (1a), F (1b)), [C5Me5Ti(mu-O)](4)F[(mu-F)AlMe3](3) (2b), [C5Me5Ti(mu-O)](4)F-3[(mu-F)Al(CH2Ph)(3)] (3a), and [C5Me5Ti(mu-O)Et](4) (4) have been determined by X-ray diffraction studies. Both chlorides and fluorides in la and Ib, respectively, are oriented to the exo position of their "butterfly" structures. The bond lengths of the terminal fluorines (T-i-F-t) in compounds 2b and 3a are discussed with respect to the deviation from the bond lengths of the bridging fluorines (Ti-F-b-Al). The structure of 4 displays a nonplanar Ti4O4 ring conformation as shown in 2b and 3a. [References: 39]