Synthesis, Characterization, and Single-Crystal X‑ray Structures of Refractory Metal Compounds as Precursors for the Single-Source Chemical Vapor Deposition of Metal Nitrides

The chemical vapor deposition of
refractory metal nitrides requires
volatile precursors and has previously been achieved by using metal
complexes containing a variety of imide ligands. Recently, the 1,4-di-tert-butyl-1,3-diazabutadiene (DAD) adduct of bis(tert-butylimide)­dichloride­molybdenum(VI) was
shown to be an excellent precursor for the single-source CVD of Mo2N thin films. Leveraging the success of this work, we prepared
chromium and tungsten compounds with the same framework. Additionally,
the framework has been modified slightly to allow the isolation of
mono(tert-butylimide)trichloride complexes of vanadium,
niobium, tantalum, and molybdenum(V) to extend the search for new
vapor-phase precursors. These compounds were all fully characterized
using the standard methods of multinuclear magnetic resonance spectroscopy,
combustion analysis, and single-crystal X-ray diffraction. Their thermal
properties were determined by using thermogravimetric analysis and
differential scanning colorimetry to assess their utility as vapor-phase
precursors. Finally, preliminary deposition studies were carried out
to investigate their potential as single-source CVD precursors.