摘要:
The syntheses of the 1,3,5-trimethyl- and tri-tert-butyl-1,3,5-triazacyclohexane-supported imido complexes [M(NR)(R'(3)tach)Cl-2] (M = Ti or Zr (NMR only); R = Bu-t or 2,6-C6H3Pr'(2); R' = Me or Bu-t) are reported, along with that of the thermally robust dibenzyl derivative [Ti(NBut)(Me(3)tach)(CH2Ph)(2)]. The tert-butylimido ligand in [Ti(NBut)(Me(3)tach)Cl-2] undergoes exchange with ArNH2 (Ar = 4-C6H3Me or 2,6-C6H3Pr'(2)) to form the corresponding arylimides [Ti(NAr)(Me(3)tach)Cl-2]. The Me(3)tach ring in [Ti(NR)(Me(3)tach)Cl-2] undergoes slow exchange with Bu(3)(t)tach or Me(3)tacn (1,4,7-trimethyl-1,4,7-triazacyclononane) to give the ring-exchanged products [Ti(NR)(Bu(3)(t)tach)Cl-2] and [Ti(NR)(Me(3)tacn)Cl-2], respectively. The complexes [Ti(NR)(Me(3)tach)X-2] (R = Bu-t or 2,6-C6H3Pr2i; X = Cl or CH2Ph) exhibit room-temperature dynamic NMR behaviour via an unusual trigonal twist of the facially coordinated Me(3)tach ligand, and the activation parameters for these processes have been measured and are discussed. The X-ray structures of [Ti(NR)(Bu(3)(t)tach)Cl-2] (R = Bu-t or 2,6-C6H3Pr2i) and [Ti(NBut)(Me(3)tach)(X)(2)] (X = Cl or CH2Ph) are reported. Me(3)tach and Bu(3)(t)tach = 1,3,5-trimethyl- and tri-tert-butyl-1,3,5-triazacyclohexane, respectively. (C) 2000 Elsevier Science S.A. All rights reserved.