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).