Dinuclear dialkoxo-bridged cyclopentadienylsiloxo titanium complexes

作者：Postigo Lorena; Sanchez Nieves Javier; Royo Pascual^*; Mosquera Marta E G

来源：Dalton Transactions, 2009, (19): 3756-3765.

DOI：10.1039/b820092k

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) 1a, 1,2-O(2)C(6)H(4) 1b, 1,2-(OCH(2))(2)C(6)H(4) 1c, O(2)SiPh(2) 1d) were obtained by reaction of [(TiCl(2))(2)(mu-{(eta(5)-C(5)Me(4)SiMeO)(2)(mu-O)})] (A) with the corresponding dilithium salt (1a) or diol (1b, 1c, 1d). Alkylation of 1a and 1b 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 2a, Bz 3a; O(2)L = 1,2-O(2)C(6)H(4), R = Me 2b, Bz 3b). Addition of four equiv. of LiOiPr to A afforded [{Ti(OiPr)(2)}(2)(mu-{(eta(5)-C(5)Me(4)SiMeO)(2)(mu-O)})] (4). Reaction of 1a 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)})] (5), whereas the same reaction of 1b with Al(C(6)F(5))(3) produced the oxo-alane adduct [(TiCl)(2)(mu-O(2)L)(eta(5){(eta(5)-C(5)Me(4)SiMeO)(2)(mu-O center dot Al{C(6)F(5)}(3))})] (O(2)L = 1,2-O(2)C(6)H(4) 6) which was further transformed to give a mixture of 5 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) 7). One benzyl group of complexes 3 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 8B, Al 8Al; O(2)L = 1,2-O(2)C(6)H(4), E = B 9B), although 8Al 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)] ( 10) was identified, and compound 9B was also unstable at ambient temperature. Polymerization of epsilon-caprolactone was only achieved with the tetraalkoxo compound 4. All of these complexes were characterized by NMR spectroscopy and 1a, 1b and 7 by X-ray diffraction studies.

• 出版日期2009