Cut-and-Pasting Ligands: The Structure/Function Relationships of a Thermally Robust Mo(VI) Precursor

The bis(tert-butylimido)-molybdenum(VI) framework has previously been used for the successful atomic layer deposition and chemical vapor deposition of many molybdenum-containing thin films. We have now prepared and fully characterized a new thermally robust bis(tert-butylimido)molybdenum(VI) complex, bis(tert-butylimido)-bis(N-2-(tertbutyliminomethyl)pyrrolato)-molybdenum(VI), (tBuN)2Mo(PyrIm)2 (1), that incorporates two N,N’-κ2-monoanionic ligands. The volatility and thermal stability of 1 was measured using thermogravimetric analysis and differential scanning calorimetry, where it was found to achieve a 1 Torr of vapor pressure at 212 ºC and had an onset of thermal decomposition at 273 ºC. Comparison of its thermal properties to the known ALD precursor (tBuN)2Mo(dpamd)2 (dpamd = N,N’-diisopropyl-acetamidinato) showed that 1 exhibits a similar volatility, but with a 78 ºC improvement in thermal stability. Since 1 exhibits an excellent thermal range (61 ºC), it should be further explored for use as a vapor deposition precursor.