Synthesis of Mono- and Dinuclear Aluminum Complexes Bearing Aromatic Amino-Phenolato Ligands: A Comparative Study in the Ring-Opening Polymerization of Cyclohexene Oxide

Aluminum Complexes Bearing Aminoquinoline Ligands with Different Pendant Donors: Remarkable Impact of Hemilability on the Ring-Opening Polymerization of ε-Caprolactone

“…It is suggested that deactivation of complexes Al2 and Al3 is due to the increased amount of impurities present in larger quantities of the monomer. Similar observations have been made earlier. − To gain deeper insights into this unusual observation, DFT calculations for the transition states of Al1 – Al3 interacting with the ε-CL monomer (Figure S30) were carried out. In the presence of 1 equiv of BnOH as the initiator, complexes Al1 – Al3 should react with BnOH first and form the corresponding BnO-Al catalysts ( BnO-Al1 , BnO-Al2 , and BnO-Al3 , respectively).…”

Studies on the Coordination Patterns of Diamine-Bridged Tetraphenoxy Ligands with Group 3 and 4 Metals

“…Proligand 1a-H 4 was prepared and isolated in 70% yield using the published procedure (Scheme ), while for the synthesis of the arene-bridged congeners 1b-H 4 and 1c-H 6 , a procedure similar to that described in the literature was applied (Scheme ). The product 1b-H 4 was isolated in good yield and characterized by NMR spectroscopy and elemental analysis . Unexpectedly, the same condensation reaction of 2-(bromomethyl)­phenol with 2,6-diaminopyridine afforded with lower yield (20%) compound 1c-H 6 whose structure was established by NMR spectroscopy and X-ray crystallography (Figures S1, S2, and S24, respectively).…”

“…Deuterated solvents (benzene- d 6 , toluene- d 8 , THF- d 8 > 99.5% D, Deutero GmbH, and Euroisotop) were vacuum-transferred from Na/K alloy into storage tubes. The proligands and metal precursors 2-(bromomethyl)-4,6-di- tert -butylphenol, 1a-H 4 , 1b-H 4 , Me 3 SiCH 2 Li, Ln­(CH 2 SiMe 3 ) 3 (THF) 2 (Ln = Sc, Y), and Hf­(CH 2 Ph) 4 were prepared according to the published procedures. 2-Phenylpyridine was dried with 4 Å molecular sieves and stored under argon.…”

Aluminum Complexes Supported by Ph2P‐Functionalized Anilido‐Pyridine Ligand Platform: Synthesis, Structure and Evaluation as Frustrated Lewis Pairs

“…Then, neutral aluminum complexes were explored as initiators of ring-opening copolymerization (ROCOP) of CO 2 with cyclohexene oxide (CHO) (Table 1). [41] Though, in all cases only atactic homopolymers of poly(CHO) were isolated, thus, being completely void from carbonate linkages, as judged by 13 C NMR spectroscopy. Dinuclear 3a-Al 2 rapidly polymerized CHO at 80 °C affording bimodal polymers (entries 1 and 2).…”

“…In general, the molecular weight characteristics of these polymers are comparable to those reported for poly(CHO)s obtained with other neutral methyl-aluminum initiators. [41] Given epoxide can replace the coordinated Et 2 O molecule in 5 a-Al, [34] we decided to assess the potential of this cationic system in polymerization of CHO (entries 4-7). The corresponding reactions proceeded quite rapidly during the first 15-45 minutes with a turnover frequency (TOF) up to 1080 h À 1 , though they failed to achieve high conversions even after 24 hours, likely due to a prompt decomposition of active species.…”