Molecular Transformations for Direct Synthesis of Thorium Dioxide Films

New Th(IV) complexes with high volatility were synthesized and applied as molecular single‐source precursors for chemical vapor deposition (CVD) of ThO 2 thin films. The change in the steric profile of alkoxide ligands and concomitant reduction in the molecular weight of [Th(L) 2 (OR) 2 ] ( 1‐OR , R= iso ‐propyl ( 1‐O i Pr ) or tert ‐butyl ( 1‐O t Bu ), L=N‐(4,4,4‐trifluorobut‐1‐ene‐3‐one)‐methoxyethylamide)) had a profound effect on the vapor pressure (at 10 −5 mbar) evident in the drop in sublimation temperature to 100 °C for the iso‐propoxide derivative against 130 °C observed for the tert‐( 1‐O t Bu) . Hirshfeld surface analysis of both complexes showed different degrees of intermolecular H⋅⋅⋅F interactions responsible for the observed differences in the volatilities of the two complexes. Both mixed‐ligand compounds ( 1‐O i Pr , 1‐O t Bu ) were applied in the CVD process to deposit thorium oxide thin films without any carrier or reactive gas that verified their suitability as single‐source precursors to ThO 2 coatings. Thin films of ThO 2 were grown at 500 °C and 600 °C on Si/SiO 2 substrates, which showed presence of C, N, and F presumably originating from the incorporation of ligand fragments in the growing CVD deposits. Subsequent calcination of CVD‐grown ThO 2 films at 800 °C in air led to phase pure ThO 2 coatings with uniform morphology.