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Direct Reactions of Iodine-Activated Rare-Earth Metals with Phenols of Varying Steric Bulk



Sonication of rare-earth metals activated by iodine with 2,6-di-tert-butyl-4-methylphenol (HOdbmp), 2,6-diphenylphenol (HOdpp) and mesitol (HOmes) in acetonitrile or tetrahydrofuran (thf) yielded [La(Odbmp)3(NCMe)2], [Eu(Odbmp)2(thf)3], [Ln(Odpp)3(thf)2] (Ln = La, Nd), [Eu(Odpp)2(dme)2] (after workup with 1,2-dimethoxyethane), [Ln2(Omes)6(thf)4] (Ln = La, Nd), [Y(Omes)3(thf)3] and [Eu3(Omes)6(thf)6] in reactions controlled both by the bulk of the phenol and of the metal. It was noteworthy that EuII complexes were obtained under the conditions used. The method offers a general, environmentally friendly, metal-based route to rare-earth phenolates with prospects for wide application. Some comparison reactions of Ln metals with Hg(C6F5)2 and the phenols were also carried out and the additional complex [Eu(Odpp)3(dme)] was isolated. Structures of the new low-coordinate complexes [La(Odbmp)3(NCMe)2]·2MeCN, [Eu(Odpp)2(dme)2] and [Eu(Odpp)3(dme)], and a new polymorph of [Eu(Odbmp)2(thf)3]·thf, were determined.