Effect of the Nature of N-Donor Ligands on the Structure of Mixed-Anion Europium Benzoate Pentafluorobenzoate Compounds

Abstract The study addresses mixed-anion Eu(III) complexes with benzoic (Bz) and pentafluorobenzoic (Pfb) acid anions and 2,2'-bipyridine(Bpy), 4,4'-dimethyl-2,2'-bipyridine (Me 2 Bpy), 4,4'-di- tert- butyl-2,2'-bipyridine ( t -Bu 2 Bpy), 4,4'-dinonyl-2,2'-bipyridine(Nn 2 Bpy), and 3,4,7,8-tetramethyl-1,10-phenanthroline: [Eu 2 (Bpy) 2 (Pfb) 2.4 (Bz) 3.6 ] ( I ), [Eu 2 (Me 2 Bpy) 2 (Pfb) 2.5 (Bz) 3.5 ] ( II ), [Eu 2 (Nn 2 Bpy) 2 -(Pfb) 3.5 (Bz) 2.5 ]·2MeCN ( III ), [Eu 2 ( t -Bu 2 Bpy) 2 (Pfb) 5.5 (Bz) 0.5 ] n ·2 n MeCN ( IV ), and [Eu 2 (Me 4 Phen) 2 -(Pfb) 4.8 (Bz) 1.2 ] n ( V ). According to X-ray diffraction data, in the structures of all compounds, Bz – and Pfb – anions are refined simultaneously in various ratios in some anion sites. It was shown that varying the substituents in the N-donor ligands affects the composition and geometry of the formed complexes. The complexes were characterized by X-ray diffraction, IR spectroscopy, and CHN analysis. The structures and crystal packing of the obtained complexes were analyzed in detail. The major contribution to stabilization of the crystal packing is made by π···π, C–H···F, and C–F···π interactions.