Cationic titanium complexes containing alkoxide and carboxylate pincer ligands; Noninnocent role of the anionic moieties in their reactivity

摘要

The reactions of [Cp*TiMe{(OCH2)(2)py}] (1) and [Cp*TiMe{(OOC)(2)py}] (2) with triflic acid (HOTf) in the presence of a series of Lewis bases, such as water, pyridine, and tert-butylpyridine, give rise to the corresponding cationic species, namely [Cp*TiL{(OCH2)(2)py}]+OTf- (3-5) and [Cp*TiL{(OOC)(2)py}]+OTf- (6, 7). Similar processes with 1 and HOTf in the presence of 2,6-pyridinedimethanol and 2-pyridinemethanol lead to the binuclear complexes [{Cp*Ti((OCH2)(2)py)}(2){mu-(HOCH2)(2)py}]OTf2 (8) and [Cp*Ti{(OCH2)(2)py}{(HOCH2)py}]OTf (9), respectively. In an unusual process, the reaction of 3 with NaBPh4 or 1 with B(C6F5)(3) yields hydroxo-containing binuclear species, namely [{Cp*Ti((OCH2)(2)py)}(2)(mu-OH)][BPh4] (10) and [Cp*Ti(mu-OH){(OCH2)(2)py}][BMe(C6F5)(3)] (12), respectively. The X-ray molecular structures of 10 and 12 have been established. Finally, the titanium-aluminum heterometallic complex [Cp*Ti{(OCH2)(2)py}(mu-O-AlMeOTf)] (16) has been prepared by reaction of 3 with AlMe3.