Symmetric and asymmetric samarium alkoxide derivatives of bridging sulfur biphenolate and binaphtholate ligands; synthetic, structural, and catalytic studies

The new thio-binaphthol 2,2′thiobis(3,6-di-tert-butylnaphth-2-ol), and a phenolic analogue 2,2′thiobis(6-tert-butyl-4-methyl phen-2-ol) react with the Sm(III) aryloxide [Sm(OC6H3But2-2,6)3] to give the first f-element complexes supported by S-bridged biphenolate or binaphtholate ancillary ligands, [Sm{1,1′-S(2-OC10H4But2-3,6)2}(OC6H3But2-2,6)]2 and [Sm{1,1′-S(2-OC6H2But-3-Me-5)2}(OC6H3But2-2,6)]2. Symmetric and asymmetric derivatives of both ligands have been prepared by careful tuning of the preparative procedure, the asymmetric naphtholate derivative, and the ligand from which it derives have both been structurally characterised. The asymmetric derivatives are found to be highly selective catalysts for diol desymmetrisation.