Aluminium metal complexes supported by amine bis-phenolate ligands as catalysts for ring-opening polymerization of ε-caprolactone

Abstract

A family of aluminium complexes supported by dianionic amine bis(phenolate) ligands are described. Treatment of ligand precursors1.1 molar equivalent of AlMe 3 in toluene affords MeAl(O 2 NN Py ) (1) and MeAl(O 2 NN Me ) (2) as five-coordinate aluminium methyl complexes, which further react with one equivalent of benzyl alcohol affording (C 6 H 5 CH 2 O)Al(O 2 NN Py ) (3) and (C 6 H 5 CH 2 O)Al(O 2 NN Me ) (4) as five-coordinate aluminium benzyloxy complexes. The molecular structures are reported for compounds 1 and 4. Compounds 3 and 4 show excellent catalytic activity toward the ring-opening polymerization of ε-caprolactone.

Synthesis, characterization and photoluminescence of aluminum N-aryloxo functionalized β-ketoiminate complexes

“…Compared with a related amine-bridged bis(phenollate) aluminum methyl complex [15], the bridging Al− O(Ar) bond lengths are longer (0.1891 (1) (1) nm is comparable with those found in dimeric β-ketoiminate aluminum chlorides [16].…”

Metallomacrocycles as ligands: synthesis and characterisation of aluminium-bridged bisglyoximato complexes of palladium and iron

“…Methylaluminium species were prepared in situ by a modification of literature procedures and used as precursors for protonolysis reactions with glyoximes (Scheme 1). 51,52 Treatment of acenaphthenequinonedioxime (glyoxime b, Scheme 1), which is sparingly soluble in THF, with 2 led to a homogeneous mixture indicating that a reaction occurred. The 1 H NMR spectrum in C 6 D 6 contains signals corresponding to both the phenoxide ligand and the dioximato backbone.…”

Dimethyl-Aluminium Complexes Bearing Naphthyl-Substituted Pyridine-Alkylamides as Pro-Initiators for the Efficient ROP of ε-Caprolactone

“…Unfortunately, on treatment of 1a with one equivalent of benzyl alcohol in C6D6 a mixture of products was formed as evidenced by a series of the peaks in 1 H NMR spectrum in the region characteristic of the Al-OCH2Ph protons (between δ 4.9-5.4) [19,68]. This observation would suggest that the presence of ε-CL is crucial for generating the single active Al-benzyloxide species.…”

“…As the catalytic properties of the aluminum species employed are greatly influenced by the ancillary ligand (both electronically and sterically), a wide variety of multidentate ligand architectures have been developed and investigated in this field. While early reports focused on dianionic tetradentate ligands [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], more recent studies have highlighted the considerable potential of using tridentate [21][22][23][24][25][26][27][28][29] and bidentate [20,[30][31][32][33][34][35][36][37][38][39][40][41][42] ligand sets as monoanionic ancillaries for potent and well-behaved AlR2-based (R = alkyl) pro-initiators.…”