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 = 2,2′-thiobis(4,6-dimethylphenolate); Stdiol = 2,2′-thiobis(4,6-diterbuthylphenolate)), were synthesised by methane elimination reactions from GaMe₃ and the diol proligands SmdiolH₂ and StdiolH₂. 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 ^tBuLi 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.