Molecular assemblies of trichloride neodymium and europium complexes chelated by 1,10-phenanthroline

Four trichloride lanthanide (neodymium or europium) complexes (1–4) have been solvothermally synthesized with the 1,10-phenanthroline (phen) chelate in ethanol solvent and their structures have been characterized by single-crystal X-ray diffraction analysis. Depending on the Ln/phen ratio, different motif nuclearities have been observed. With Ln/phen = 1/2, a dinuclear species with μ2-Cl2 edge-sharing bridge is formed with neodymium, NdCl3(phen)2 (1), whereas a mononuclear complex appears with europium, EuCl3(phen)2 (4) with an unusual pentagonal bipyramid for the lanthanide center (coordination 7). When Ln/phen ratio increases (1/1), an identical complex is obtained with Nd (2) or Eu (3). It is a monohydrated complex LnCl3(H2O)(phen)2 with one water molecule completing the coordination sphere of the lanthanide. For all compounds, each rare-earth cation is chelated by two distinct phen ligands. Thermal behavior of complexes 1 and 2 are discussed (by means of thermogravimetric analysis and X-ray thermodiffraction) as well as the luminescence spectra of europium-based complexes 3 and 4 (Supplementary Material).

Graphical abstractA series of trichloride neodymium or europium complexes has been solvothermally synthesized in ethanol and structurally characterized. Anhydrous dinuclear NdCl3(phen)2 or mononuclear EuCl3(phen)2 species have been isolated with a Ln/phen ratio of 1/2, whereas monohydrated mononuclear LnCl3(H2O)(phen)2 forms crystallized from Ln/phen ratio of 1/1.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Solvothermal syntheses of dinuclear and mononuclear Nd- or Eu-trichloro complexes. ► Single-crystal X-ray diffraction structural determination. ► Thermogravimetric and X-ray thermodiffraction analyses. ► Luminescence spectra of the Eu(III) complex.