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.