Titanium(IV) and Zirconium(IV) amido complexes derived from the azaoxa macrocycle 3,3-dimethyl-1,5-diaza-8-oxacyclodecane.
The novel tridentate azaoxa macrocycle [O(NH)2], 3,3-dimethyl-1,5-diaza-8-oxacyclodecane, can be singly or doubly lithiated with (n)BuLi at the secondary amine N atoms, giving [O(NH)N]Li and [O(N)2]Li2, respectively, and further elaborated with introduction of TMS substituents via reaction with (TMS)Cl. Aminolysis of [Ti(NMe2)2Cl2] or [Zr(NR2)2Cl2(THF)2] with [O(NH)2] in toluene gave the distorted octahedral M[O(NH)N](NR2)Cl2 (M = Ti, R = Me; M = Zr, R = Me or Et), in which the macrocycle functions as a monoanionic ligand via an amido, an amine, and an ether functionality. Salt metathesis of [Zr(NEt2)2Cl2(THF)2] with [O(NH)N]Li in toluene afforded Zr[(O(NH)N)](NEt2)2Cl, the structure of which also confirms tridentate macrocycle coordination via one amido, one amine, and one ether group; in contrast, analogous salt metathesis involving [Zr(NEt2)2Cl2(THF)2] and [O(N)2Li2] gave the "sandwich" complex [(ON2)2Zr], with the macrocycle behaving as a dianionic ligand (Porter, R. M.; et al. Dalton Trans. 2005, 427). Finally, treatment of [O(NH)2] with AlMe3 gave the simple donor-acceptor adduct [O(NH)2]AlMe3, which resisted alkanolysis by prolonged heating. In the presence of MAO the new zirconium, titanium, and aluminum complexes show low activity in the polymerization of ethylene.
Porter
Robin M
RM
School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom.
Danopoulos
Andreas A
AA
Reid
Gillian
G