Organogallium complexes incorporating tridentate thioetherbiphenolate ligands 2,2′-thiobis(4,6-di-tert-butylphenolate), Stdiol and 2,2′-thiobis(4,6-dimethylphenolate), Smdiol

Abstract

Organogallium(III) thioetherbisphenolate complexes of general formulae SmdiolGaMe-THF (1), StdiolGaMe-THF (2), SmdiolGaMe (3) and StdiolGaMe (4) (Smdiol ¼ 2,2 0 -thiobis(4,6-dimethylphenolate); Stdiol ¼ 2,2 0 -thiobis(4,6-diterbuthylphenolate)), were synthesised by methane elimination reactions from GaMe 3 and the diol proligands SmdiolH 2 and StdiolH 2 . The molecular structure of 1 is monomeric and shows the Ga centre adopting a trigonal bipyramidal structure with one of the apical positions occupied by the oxygen atom of a coordinated THF molecule. While the solution spectroscopic data of 4 is in support of a monomeric, probably tetrahedral, species its solid state structure shows a polymeric array built upon intermolecular sulphur-to-gallium interactions resulting in a distorted trigonal bipyramid. The Smdiol derivatives 1 and 3 show modest catalytic activities in Diels-Alder cycloaddition reactions of methacrolein and cyclopentadiene. In addition, StdiolGaH (7) is conveniently synthesized from reaction of StdiolGaCl and t BuLi at room temperature. Compound 7 readily hydrolyses in the presence of trace amounts of water leading to StdiolGa(OH) (8) whose solid state structure was determined.

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

“…In general, the coordination geometries of 2-4 and 6 are similar to those reported by us for solvated gallium complexes [(Smdiol)GaMe-THF] and [(Stdiol)GaMe-THF]. 10 For complexes 2-4 and 6 the calculated angular structural parameter, c, introduced by Konno et al for the four complexes is between 0.82-0.90. The structural parameter c is 1 for an ideal tbp geometry whilst it is 0 for an ideal sqp geometry.…”

“…These complexes exhibited modest catalytic activities in Diels-Alder cycloaddition reactions of methacrolein to cyclopentadiene. 10 This can be compared with the present work on aluminium complexes which exhibit better catalytic activity. Herein we describe the use of the Smdiol and Stdiol ligands for complexation on aluminium organyls and chlorides in coordinating and noncoordinating solvents along with the exploration of their homogeneous catalytic activity in the Diels-Alder reaction of methacrolein to cyclopentadiene.…”

“…Along these lines, a variation of the bis(phenoxide) ligands in which a thioether functionality is added has been used as a platform for the preparation of group 4 and group 13 complexes that show catalytic activities in the polymerization of olefins, 9 Diels-Alder cycloaddition reactions, 10 and in the ring opening polymerization of oxiranes. 11 Improvements in the catalytic activity of such complexes have been observed as a result of the introduction of the thioether functionality.…”