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[摘要]：In this work, quartz crystal microbalance (QCM) and quadrupole mass spectrometry (QMS) have been used for in situ investigations of the D2O and ozone processes at 250 degrees C for (BuN)-Bu-t=Nb(NEt2)(3) and (BuN)-Bu-t=Ta(NEt2)(3). In the D2O processes, the ligand exchange reaction is demonstrated by the formation of (D2NBu)-Bu-t and DNEt2 as byproduct. For (BuN)-Bu-t=Nb(NEt2)(3), one out of three -NEt2 ligands is exchanged during the precursor pulse, whereas for (BuN)-Bu-t=Ta(NEt2)(3), it is 1.7 -NEt2 ligands and 0.3 =(NBu)-Bu-t ligand that are exchanged during the (BuN)-Bu-t=Ta(NEt2)(3) pulse. This difference in the reaction mechanism of the two structurally similar precursors can be explained by the differences in their bond polarities as shown by our quantum chemical calculations. Regarding the ozone processes, QCM results point to a molecular adsorption of (BuN)-Bu-t=Nb(NEt2)(3) and an exchange of at least two ligands for (BuN)-Bu-t=Ta(NEt2)(3). QMS indicates a typical ozone combustion byproduct, such as CO2 (m/z = 44), CO (m/z = 28), H2O (m/z = 18), and NO (m/z = 30) or N2O (m/z = 44, 30). A major fragment of both types of ligands (m/z = 58) is also observed. Precise quantification of these byproduct is rendered impossible due to overlapping of different species with the same m/z value. However, careful examination of the data reveals general information on the different contributions to the signal. |
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