Synthesis and structural analysis of heteroleptic molybdenum(VI) complexes with N-alkoxy carboxamide ligands

Bis(imido)molybdenum (VI) complexes have been studied for application as precursors in the molybdenum thin film deposition process, because of their structural stability and volatility. In this study, we introduced N -alkoxy carboxamide ligands to bis( tert -butylimido)molybdenum complex for synthesis of novel heteroleptic molybdenum(VI) complexes. Complexes, Mo(N t Bu) 2 (mdpa) 2 (mdpaH = N -methoxy-2,2-dimethylpropanamide) ( 1 ), Mo(N t Bu) 2 (edpa) 2 (edpaH = N -ethoxy-2,2-dimethylpropanamide) ( 2 ), Mo(N t Bu) 2 (empa) 2 (empa = N -ethoxy-2-methylpropanamide) ( 3 ), Mo(N t Bu) 2 (mpa) 2 (mpaH = N -methoxypropanamide) ( 4 ), Mo(N t Bu) 2 (bdpa) 2 (bdpaH = N - tert -butoxy-2,2-dimethylpropanamide) ( 5 ) and Mo(N t Bu) 2 (etfa) 2 (etfaH = N -ethoxy-2,2,2-trifluoroacetamide) ( 6 ) were synthesized by double substitution reactions of Mo(N t Bu) 2 Cl 2 (DME) (DME = 1,2-dimethoxyethane) and sodium salt of N -alkoxy carboxamide in hexane. All new complexes were then characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA). To confirm the precise structure, complex 1 was analyzed by single crystal X-ray diffraction (SC-XRD). An X-ray single crystallographic study showed that complex 1 exists in a distorted octahedral molecular geometry, in which molybdenum is bound to the N- and O- atoms of the respective ligand. Thermal properties of the complexes were investigated by thermogravimetric analysis (TGA). It showed that all complexes were both vaporized and decomposed in the analysis range. The volatility of complex 4 was measured by vapor pressure measurement and it indicates that complex 4 has enough volatility (1 Torr @ 74.8 °C) for the vapor-phase deposition process. • New molybdenum complexes were synthesized using N-alkoxy carboxamide ligands. • Structural analysis showed that the complex has a distorted octahedral geometry. • TGA and vapor pressure exhibited that the complexes have enough volatility. • Synthesized complexes can be applied to deposit molybdenum oxide film.