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Bond dissociation free energy (BDFE) for the dissociation of flexible ligands from their pentacoordinate bis(tert-butylimido)-dichloromolybdenum(VI) complexes to form the free ligand
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![Figure 2. Solid-state structure of [( t OctN)2Mo(μ-Cl)2]∞ (0e)∞ showing...](publication/360970091/figure/fig1/AS:11431281100454529@1669357593088/Solid-state-structure-of-t-OctN2Mom-Cl2-0e-showing-the-dimeric-unit-left-and_Q320.jpg)
The bis(tert-butylimido)-molybdenum(VI) framework has been used successfully in the design of vapor-phase precursors for molybdenum-containing thin films, so understanding its thermal behavior is important for such applications. Here we report the thermal decomposition mechanism for a series of volatile bis(alkylimido)-dichloromolybdenum(VI) adduct...
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Context 1
... the calculated barriers to the decomposition via formation of tert-butylamido and nitrido moieties (and free isobutylene), were not only significantly lower than those of the hexacoordinate isomers (37.0 < ΔG ‡ penta < 39.2 kcal·mol −1 ), but were also lower than the free monomer and higher than the free dimer for the same pathway (Table 3). Finally, the natural logarithm of the BDFE for the dissociation of the monodentate ligands from the pentacoordinate complexes to yield the dimer (0a)2 showed a strong linear correlation with the decomposition temperature of the parent complexes (R 2 = 0.917, Figure 7). Thus, the observed thermal stability of the hexacoordinate complexes was controlled by the free energy of their pentacoordinate isomers relative to their free ligand and dimer (Figure 7). ...
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... the natural logarithm of the BDFE for the dissociation of the monodentate ligands from the pentacoordinate complexes to yield the dimer (0a)2 showed a strong linear correlation with the decomposition temperature of the parent complexes (R 2 = 0.917, Figure 7). Thus, the observed thermal stability of the hexacoordinate complexes was controlled by the free energy of their pentacoordinate isomers relative to their free ligand and dimer (Figure 7). and free dimer (0a)2 (inset) and the correlation of ln(BDFE) with the onset of decomposition, as observed by DSC, showing that the free energy of the dimer relative to the pentacoordinate intermediate determines the observed decomposition temperature of the hexacoordinate parent complexes. ...
Context 3
... key intermediates controlling the relative decomposition temperatures of the bis(tertbutylimido)-dichloromolybdenum(VI) adducts could now be identified using our combined experimental and computational results (Figure 7). First, all ligands had BDEs and BDFEs that were comparable, but lower, than the lowest decomposition barrier enthalpies and energies (i.e., BDE < ΔH ‡ nit and BDFE < ΔG ‡ nit). ...
