Volatile Single-Source Precursors for the Low-Temperature Preparation of Sodium-Rare Earth Metal Fluorides

Heterometallic single-source precursors for the preparation of sodium-rare earth metal fluorides are reported. Fluorinated β-diketonates NaRE(hfac)₄ (RE = Y (1), Er (2), and Eu (3); hfac = hexafluoroacetylacetonate) have been obtained on a large scale, in high yield, via one-pot reaction that utilizes commercially available starting reagents. The solid-state structures of the title complexes consist of 1D polymeric chains with alternating [Na] and [RE(hfac)₄] units. Compounds 1-3 are highly volatile and exhibit a fair stability in open air. Mass spectrometric investigation indicates the presence of heterometallic fragments in the gas phase. The presence of heterometallic species in solutions of coordinating solvents has also been confirmed. Decomposition of heterometallic precursors in argon atmosphere was shown to yield phase-pure sodium-rare earth metal fluorides. Low decomposition temperature effectively allows for a high degree of control over the formation of both kinetic α-phases and thermodynamic β-phases of target NaREF₄ (RE = Y, Er, and Eu) materials.