Neodymium β-diketonate glyme complexes: Synthesis and characterization of volatile precursors for MOCVD applications

The monoglyme [CH3OCH2CH2OCH3] and diglyme [CH3O(CH2CH2O)2CH3] adducts of the neodymium tris-hexafluoroacetylacetonato [Nd(hfa)3·monoglyme·H2O and Nd(hfa)3·diglyme] have been synthesised in a single step reaction. They have been characterized by elemental analyzes, mass spectrometry, and IR spectroscopy. Single crystal X-ray diffraction studies provide evidence of a mononuclear nine-coordinated complex with a monocapped square antiprismatic structure for the Nd(hfa)3·diglyme (monoclinic system, space group P21/n; a = 9.7717(2), b = 15.5723(4), c = 20.5620(5) Å, β = 103.668(2)°; Z = 4). The Nd(hfa)3·monoglyme·H2O consists of asymmetric units containing two similar molecules (monoclinic system, space group = C2; a = 16.7057(4), b = 12.2579(4), c = 29.3734(5) Å, β = 101.170(3)°, Z = 8). The mass transport properties of these adducts have been investigated by thermogravimetric analysis which revealed high volatility and good thermal stability with a residue left lower than 3%. The Nd(hfa)3·diglyme has been successfully applied to the low-pressure metal organic chemical vapor deposition (MOCVD) of NdBa2Cu3O7−δ thin films.