Second-generation hexavalent molybdenum oxo-amidinate precursors for atomic layer deposition

The synthesis of molybdenum oxo-amidinate complexes MoO₂(R₂AMD)₂ [AMD = N,N'-di-R-acetamidinate; R = Cy (2; cyclohexyl) and ⁱPr (3)], and their characterization by ¹H, ¹³C NMR, X-ray diffraction, and thermogravimetric analysis is reported. Quartz-crystal microbalance and X-ray photoelectron spectroscopic studies confirm that 3 is an improved ALD precursor versus the R = t-butyl derivative for MoO₃ film growth. Complex 3 is accessible in higher yields (80%+), is easier to handle without mass loss, and in conjunction with O₃ as the second ALD reagent, yields nitride-free MoO₃ films.