Synthesis and characterization of two dioxidomolybdenum(VI) complexes bearing amidinato and pyrazolato ligands and their use in thin film growth and oxygen atom transfer reactions

Abstract

Treatment of anhydrous dichloro(dioxido)molybdenum with one equivalent of (1,3-di-tert-butylpyrazolato)potassium in toluene at room temperature followed by the addition of (1,3-di-tert-butylacetamidinato)lithium or (1,3-diisopropylacetamidinato)lithium afforded MoO2(tBuNC(Me)NtBu)(3,5-tBu2pz) and MoO2(iPrNC(Me)NiPr)(3,5-tBu2pz), where 3,5-tBu2pz = 1,3-di-tert-butylpyrazolato in 53% and 32% yields, respectively. The two complexes were characterized by the use of analytical and spectral methods. X-ray crystal structure determination of both complexes revealed η2-coordination of the amidinate and pyrazolate ligands and adopt pseudo octahedral geometry. These complexes sublime at a temperature range of 100–120 °C and 0.05 Torr with about 30% residue and therefore are potential precursors for the deposition of molybdenum-containing thin films using atomic layer deposition technique. Moreover, both complexes are able to oxidize triphenylphospine when added in stoichiometric or catalytic amounts to toluene or dimethyl sulfoxide solvents, respectively.