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

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-OC6H2Bu'-3,-Me-5)(2)}(OC6H3Bu2'-2,6)(THF)] and [Sm{1,1'-S(2-OC10H4Bu2'-3,6)(2)}(OC6H3Bu2'-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. (C) 2003 Elsevier Science (USA). All rights reserved.