Macrocycle-supported titanium complexes with chelating imido ligands:: Analogues of ansa-metallocenes

Reactions of 1,4-dimethyl-1,4,7-triazacyclononane (L-1a) and 1,4-diisopropyl-1,4,7-triazacyclononane (L-1b) to form 1-aminopropyl-4,7-di-R-1,4,7-triazacyclononane [R = Me (H2L3a) or Pr-1 (H2L3b)] and 1-(2-aminobenzyl)-4,7-di-R-1,4,7-triazacyclononane [R = Me (H2L5a) or Pr-i (H2L5b)] are reported. Reaction of H2L3a and H2L5a with [Ti-(NMe2)(2)Cl-2] fives the ansa-linked macrocycle-imido complexes [Ti(kappa (4)-L-3a)Cl-2] (5a) and [Ti(kappa (4)-L-5a)Cl-2] (6a). respectively, and NHMe2. Reaction of H2L3a With [Ti(NBut)Cl-2(py)(3)] gives [Ti(NBut)(kappa (3)-H2L3a)Cl-2] (7), which possesses a pendant alkylamine group that does not undergo amine/tert-butylimido group exchange to give 5a and (BuNH2)-N-t. However, reaction of H2L3b and Hr(2)L(5b) with [Ti(NBut)Cl-2(py)(3)] does give amine/tert-butylimido group exchange to form [Ti(kappa (4)-L-3b)Cl-2] (5b), [Ti(kappa (4)-L-5b)Cl-2] (8b), and (BuNH2)-N-t. The compounds Sa,b and 6a,b are isolobal analogues of group 4 ansa-metallocene complexes and relatives of titanium cyclopentadienyl-amido constrained geometry olefin polymerization catalysts. Reaction of 5b with AgOTf affords [Ti(kappa (4)-L-3b)(OTf)Cl] (8) as the major product, the crystal structure of which has been determined. Alkylation of 6b by RLi gives the dialkyl derivatives [Ti(kappa (4)-L-5b)(R)(2)] [R = M, (9) or CH2SiMe3 (10)]. The ethylene polymerization capability of the compounds 5a,b, ba,b, and 10 in the presence of methylaluminoxane has been determined and compared to that of [Ti(NBut)(kappa (3)-L-1a,L-b)Cl-2] (11a,b); in all instances, low yields of high-molecular-weight polymer art: obtained.