Synthesis, structure and catalytic activity of an air-stable titanium triflate, supported by an amine tris(phenolate) ligand

Highly active and stereoselective zirconium and hafnium alkoxide initiators for solvent-free ring-opening polymerization of rac-lactide

“…Since the first report of group 4 amine tris(phenolate) complexes, 17 there has been considerable interest in their structure and reactivity. 13,[18][19][20][21] Recent results have highlighted the potential of amine tris(phenolate)s in ROP 13,16,20 and have prompted us to investigate the potential utility of Group 4 complexes as stereoselective initiators for ROP of rac-LA. Ti, Zr and Hf complexes of the bulky amine tris(phenolate) precursor LH 3 were prepared and isolated as crystalline solids (1-3, respectively, Scheme 1).yz A single crystal X-ray structure of 3z (Fig.…”

Aryloxide-based multidentate ligands for early transition metals and f-element metals

“…The isopropoxide complexes are found to be poor catalysts, while weaker metal-ligand coordination of the triflate relative to the iso-propoxide enhances activity for the formal aza-Diels-Alder reaction between imine and diene [65a]. Complexes [12 R ]Ti(OR 0 ) initiated the ringopen polymerization of L-and rac-lactide, producing isotactic and atactic polymers, respectively [65]. It is Scheme 25.…”

“…The titanium complexes [12 R ]Ti(OR 0 ) were straightforwardly prepared as shown in Scheme 26 [64][65][66][67]. The structures of these mono-ligand complexes can be described as a 3-bladed turbine of C 3 symmetry and are maintained in solution on the NMR time scale at ambient temperature.…”

Titanium‐catalyzed esterification reactions: beyond Lewis acidity

“…The catalysts based on the tetradentate aminotriphenolate ligands are robust, display remarkable stability to hydrolysis and are stable under acidic conditions. [29][30][31][32] This can be of importance for the application of these complexes, and the stability also allows the isolation of relevant reaction intermediates. The steric and electronic properties of the tetradentate aminotriphenolate ligand can be modified, making it a perfect platform for optimization of catalyst properties and a detailed mechanistic study ( Figure 1).…”