Direct reaction of iodine-activated lanthanoid metals with 2,6-diisopropylphenol†
Rare earth metals activated with ca. 2% iodine react directly with 2,6-diisopropylphenol (HOdip) in tetrahydrofuran (thf), 1,2-dimethoxyethane (dme), and dig–dme (dig = di(2-methoxyethyl) ether) to give solvated phenolate complexes [Ln(Odip)3(thf)n] (Ln = La, Nd, n = 3; Ln = Sm, Dy, Y, Yb, n = 2), [Eu(Odip)(μ-Odip)(thf)2]2, [Ln(Odip)3(dme)2] (Ln = La, Yb) and [La(Odip)3(dig)] in good yield for Ln = La, Nd, Eu but modest yield for smaller Ln metals under comparable conditions. However, increasing the excess of metal greatly increased the yield for Ln = Y. The synthetic method has general potential, at least for lanthanoid phenolates. Comparison redox transmetallation/protolysis (RTP) reactions between Ln metals, Hg(C6F5)2 and the phenol gave higher yields in shorter time and, for Eu, gave [Eu(Odip)3(thf)3] in contrast to an EuII complex from Eu(I2). New [Ln(Odip)3(thf)3] complexes have fac-octahedral structures and [Ln(Odip)3(thf)2] monomeric five coordinate distorted trigonal bipyramidal structures with apical thf ligands. [Eu(Odip)(μ-Odip)(thf)2]2 is an unsymmetrical dimer with two bridging Odip ligands. One five coordinate Eu atom has distorted trigonal bipyramidal stereochemistry and the other is distorted square pyramidal. Whilst [La(Odip)3(dme)2] has irregular seven coordination with mer-Odip and chelating dme ligands, [Ln(Odip)3(dme)2] (Ln = Dy, Y (prepared by ligand exchange), Yb) are monomeric six coordinate with one chelating and one unidentate dme. A six coordinate fac-octahedral arrangement is observed in [La(Odip)3(dig)].