Structure of triaquatris(1,1,1-trifluoro-4-oxopentan-2-olato)cerium(III) as a possible fluorescent compound

Abstract

Luminescence due to the d–f transition of Ce3+ is quite rare in metal–organic complexes where concentrate quenching frequently occurs. One of the possible ways to avoid this is to design an architecture with elongated metal–metal distances. In the structure of the title complex, triaquatris(1,1,1-trifluoro-4-oxopentan-2-olato-κ2 O,O′)cerium(III), [Ce(C5H4F3O2)3(H2O)3], the CeIII complex is linked to neighbouring ones by hydrogen bonding. Within the complex, the CeIII atom is coordinated by nine O atoms from three 1,1,1-trifluoro-4-oxopentan-2-olate (tfa) anions as bidentate ligands and three water molecules as monodentate ligands. Thus, the coordination number of CeIII atom is nine in a monocapped square–antiprismatic polyhedron. The F atoms of all three independent CF3 groups in tfa are disordered over two positions with occupancy ratios of about 0.8:0.2. The intermolecular hydrogen bonds between the ligands involve tfa–water interactions along the [110] and [1-10] directions, generating an overall two-dimensional layered network structure. The presence of the F atoms in the tfa anion is responsible for an increased intermolecular metal–metal distance compared to that in the analogous acetylacetonate (acac) derivatives. Fluorescence from Ce3+ is, however, not observed.