3,5-Di-tert-butyl-o-benzoquinone complexes of lanthanides

Lanthanide semiquinolates Ln(SQ)3 (SQ-3,5-di-tert-butyl-o-benzosemiquinone) were prepared by the reactions of Dy, Tm, Yb with 3 equiv of 3,5-di-tert-butyl-o-benzoquinone (Q). Crystallization of thulium product from DME yields structurally characterized cluster Tm3(SQ)4(Cat)2(QH)(DME)2 (1) (Cat-3,5-di-tert-butyl-catecholate, QH-o-hydroxyphenolate). The reactions of Q with excess of metal (Sm, Eu, Tm, Yb) afford catecholates Ln2(Cat)3. For samarium product Sm4(Cat)6(THF)6 (2) X-ray diffraction study was performed. In the reaction of EuI2 with Li2(Cat) ate-complex EuLi4(LiI)2(SQ)2(Cat)2(THF)6 (3) was isolated. X-ray analysis revealed that a molecule of the complex contains two semiquinone groups, two catecholate ligands, Eu2+ cation, four Li+ cations and two LiI species bonded by bridging O and I atoms. Catecholates of Eu(II), Sm(II) as well as trivalent Ce, Nd, Gd, and Tb were obtained by treatment of corresponding lanthanide silylamides Ln[N(SiMe3)2]n (n = 2, 3) with the 3,5-di-tert-butyl-catechol. It was established that gadolinium product Gd4(Cat)6(THF)6 (4) is isostructural to samarium complex 2. Terbium catecholate Tb2(Cat)3 in THF solution revealed photoluminescence typical for Tb3+ cation.