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Postigo L, Sanchez-Nieves J, Royo P, Mosquera ME: Dinuclear dialkoxo-bridged cyclopentadienylsiloxo titanium complexes. . Dalton Trans. 2009 May 21;(19):3756-65. Epub 2009 Mar 18.
The dinuclear dialkoxo-bridged complexes [(TiCl)(2)(mu-O (2) L)(mu-{(eta (5)-C (5) Me (4) SiMeO)(2)(mu-O)})] (O (2) L = 1,2-O (2) C (2) H (4), 1,2-O (2) C (6) H (4), 1,2-(OCH (2))(2) C (6) H (4), O (2) SiPh (2)) were obtained by reaction of [(TiCl (2))(2)(mu-{(eta (5)-C (5) Me (4) SiMeO)(2)(mu-O)})] () with the corresponding dilithium salt () or diol (, , ). Alkylation of and with ClRMg afforded [(TiR)(2)(mu-O (2) L)(mu-{(eta (5)-C (5) Me (4) SiMeO)(2)(mu-O)})] (O (2) L = 1,2-O (2) C (2) H (4), R = Me , Bz ; O (2) L = 1,2-O (2) C (6) H (4), R = Me , Bz ). Addition of four equiv. of LiOiPr to afforded [{Ti (OiPr)(2)}(2)(mu-{(eta (5)-C (5) Me (4) SiMeO)(2)(mu-O)})] (). Reaction of with Al (C (6) F (5))(3) produced the elimination of the dialkoxo ligand to give [{TiCl (C (6) F (5))}(2)(mu-{(eta (5)-C (5) Me (4) SiMeO)(2)(mu-O)})] (), whereas the same reaction of with Al (C (6) F (5))(3) produced the oxo-alane adduct [(TiCl)(2)(mu-O (2) L)(mu-{(eta (5)-C (5) Me (4) SiMeO)(2)(mu-O.Al{C (6) F (5)}(3))} )] (O (2) L = 1,2-O (2) C (6) H (4)) which was further transformed to give a mixture of and [(TiCl){Ti (C (6) F (5))}(mu-O (2) L)(mu-{(eta (5)-C (5) Me (4) SiMeO)(2)(mu-O)})] (O (2) L = 1,2-O (2) C (6) H (4)). One benzyl group of complexes was abstracted with E (C (6) F (5))(3) (E = B, Al) to give the monoionic compounds [Ti (TiBz)(mu-O (2) L)(mu-{(eta (5)-C (5) Me (4) SiMeO)(2)(mu-O)})][BzE (C (6) F (5))( 3)] (O (2) L = 1,2-O (2) C (2) H (4), E = B , Al ; O (2) L = 1,2-O (2) C (6) H (4), E = B ), although was unstable in CD (2) Cl (2) evolving to a mixture of compounds where [(TiBz)(2)(mu-Cl)(mu-{(eta (5)-C (5) Me (4) SiMeO)(2)(mu-O)})][BzAl (C (6) F (5))(3 )] () was identified, and compound was also unstable at ambient temperature. Polymerization of epsilon-caprolactone was only achieved with the tetraalkoxo compound . All of these complexes were characterized by NMR spectroscopy and , and by X-ray diffraction studies. |
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