Samarium, Europium, and Gadolinium Complexes with 4-(2,1,3-Benzothiadiazol-4-ylamino)pent-3-en-2-onate

Abstract

New lanthanide complexes with 4-(2,1,3-benzothiadiazol-4-ylamino)pent-3-en-2-onate (L^–) [Ln(L)₃] are synthesized using two methods: by the reaction of Ln(N(SiMe₃)₂)₃ with the protonated form of the ligand LH (Ln = Sm, Gd) and by the reaction of LnCl₃ (Ln = Eu) with LH in the presence of KN(SiMe₃)₂ as a base. According to the X-ray diffraction data, the synthesized complexes [Ln(L)₃] · 0.5Solv (Solv = THF, C₇H₈) are isotypical (CIF files CCDC nos. 1826520, 1826521, and 1826522 for Sm, Eu, and Gd, respectively). A specific feature of the structures is the disordering of the metal atom and one of the ligands over two positions when the fragments of the ligands are arranged via the head-to-tail type occupying the same volume of the space. This probably leads to failure in the crystal lattice. The photoluminescence spectra of [Sm(L)₃] · 0.5THF are recorded. A relationship between the coordination mode of the ligand and the position of the long-wavelength band of the electron transitions in the complexes with the L^– ligand is revealed.