Sulfur-bridged phenoxide and naphthyloxide-based ligands for lanthanide chemistry and catalysis

Abstract

The development of some new lanthanide chemistry of aryloxide-based ligands is presented. The use of chelating, dianionic aryloxide ligand sets, such as sterically encumbered binolates, to allow a degree of geometrical control over the reaction chemistry of these large metal cations, is reviewed. We show how the development of potentially tridentate, dianionic, sulfur-bridged biphenolate and binaphtholate [OSO] ligands has allowed us to make new Ln(III) aryloxide complexes such as [Sm{1,1′-S(2-OC6H2But-3,-Me-5)2}(OC6H3But2-2,6)(THF)] and [Sm{1,1′-S(2-OC10H4But2-3,6)2}(OC6H3But2-2,6)(THF)]. Unusually, both symmetric and asymmetric derivatives of the [OSO] ligands may be prepared; reasons for this observation are suggested. Reactivity studies of these Sm(III) derivatives have shown them to be selective Lewis acid catalysts for the one-step monoacylation of 1,2-diols. Oxidation products of the sulfur-bridged binaphtholate ligand have been crystallographically characterized.