Dinuclear dialkoxo-bridged cyclopentadienylsiloxo titanium complexes.
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.
Departamento de Química Inorgánica, Universidad de Alcalá, Campus Universitario, E-28871, Alcalá de Henares, Madrid, Spain.
Lorena
L
Postigo
Javier
J
Sánchez-Nieves
Pascual
P
Royo
Marta E G
ME
Mosquera