Structure of tri-aqua-tris-(1,1,1-tri-fluoro-4-oxo-pentan-2-olato)cerium(III) as a possible fluorescent compound.

Abstract

This study reports the crystal structure of a cerium(III) coordination complex bearing three 1,1,1-trifluoro-4-oxopentan-2-olate (tfa) anions as bidentate ligands and three water molecules as monodentate ligands, yielding a nine-coordinate Ce center in a monocapped square-antiprismatic geometry. The CF₃ groups of all three independent tfa units exhibit positional disorder at approximately 0.8:0.2 occupancy ratios. Intermolecular hydrogen bonding between tfa and water molecules along the [110] and [1-10] directions produces a two-dimensional layered network. The fluorine substituents extend the Ce–Ce intermolecular distance relative to the analogous acetylacetonate derivatives, a structural feature intended to suppress concentration quenching. Despite this design, Ce-based luminescence was not detected experimentally.

Mechanism

Incorporation of fluorine-bearing tfa ligands was intended to increase Ce–Ce distances and thereby reduce concentration quenching, but Ce-based fluorescence emission was not observed under the experimental conditions.