Aluminium complexes derived from tridentate thioetherbis(phenolate) ligands and their activity in Diels–Alder catalysis

Abstract

Organoaluminium(III) thioetherbis(phenolate) complexes derived from 2,2-thiobis(4,6-diterbuthylphenolate) (Stdiol) and 2,2-thiobis(4,6-dimethylphenolate) (Smdiol) were prepared by reaction of AlMe3 with the diol proligands LH2 (SmdiolH2, StdiolH2). Monomeric complexes of general formulae [LAlR(L)] (L = Stdiol, R = Me, L = THF (1); L = Stdiol, R = Me, L = Et2O (2); L = Stdiol, R = iBu, L = THF) (3); L = Smdiol, R = Me, L = THF (4); L = Smdiol, R = iBu, L = THF (5)) and [LAlCl(THF)] (L = Stdiol (6); L = Smdiol (7)) were obtained when the reactions were performed in THF or Et2O in hexane or toluene, species of formulae [(L2Al)AlR2] (L = Stdiol, R = Me (8); L = Stdiol, R = iBu (9); L = Smdiol, R = Me (10)) were formed as evidenced by spectroscopic methods. Crystals suitable for X-ray diffraction studies were obtained for 2, 3, 4, 6, 8, 9 and 10. In these cases the sulfur atom coordinates to the aluminium center with Al-S bond lengths between 2.43-2.75 A adopting boat-boat conformations. Compounds 1, 3, 4, and 8 were tested in the catalytic Diels-Alder cycloaddition reaction between methacrolein and cyclopentadiene showing excellent regioselectivities with good conversion yields.

Lactide Cyclopolymerization Kinetics, X-ray Structure, and Solution Dynamics of (tBu-SalAmEE)Al and a Cautionary Tale Of Polymetalate Formation

“…In each of the independent molecules the longest Al–O bond is to the bridging ligand ether (Al(1)–O(14) = 1.9700(19); Al(2)–O(24) = 2.128(2)), consistent with this being the most labile of the ligand oxygens. Finally, the latter bond is substantially longer than dative Al–O distances in comparable molecules. ,− These data are consistent with the proposed hemilability of the ligand ether and VT-NMR data showing multiple stable conformers for 1 at 26 °C that average to trigonal bipyramidal at 80 °C (Supporting Information).…”

Versatile coordinating capabilities of thiodibenzoic acid copper complexes bearing N-donor ligands

“…It has been shown that in the absence of donor atoms in the ortho position, the diaryl sulfide acts as monodentate with only sulfur coordinating with the metal center [3]. In the presence of donor groups (hydroxyl, thiol, imines, amides) at the ortho position, diaryl sulfides are known to coordinate with metals such as aluminum [4], palladium [5], nickel [6], platinum [7], ruthenium [8], iron [9], lanthanide [10], germanium [11] and zinc complexes [12] in a tridentate manner, whereby the sulfur is involved in coordination or bidentate binding with no sulfur coordination. Diaryl sulfides containing dicarboxylate as a donor group have not been subjected to detailed study.…”

Aluminum‐Based Catalysts for Cycloaddition Reactions: Moving One Step Ahead in Sustainability

“…The catalytic activity of the Al organyl complexes can be raised by introduction of thioether functionality. Muñoz‐Hernández et al . have prepared Organoaluminum (III) thioetherbis(phenolate) complexes derived from 2,2′‐thiobis(4,6‐diterbuthylphenolate) (Stdiol) and 2,2′‐thiobis(4,6‐dimethylphenolate) (Smdiol) by reacting AlMe 3 with the diolproligands (SmdiolH2, StdiolH2) ( Scheme ) .…”