B3LYP calculations intermediates

An example of an otherwise fairly normal reactive intermediate where the harmonic approximation fails is phenylcarbene (see Fig. 17.8) Although the match beween calculated and observed IR bands is quite satisfactory across most of the spectmm, it breaks down completely in the region of 750-950 cm, where there is not even a remote similarity between the pattern of three bands predicted by B3LYP calculations (dashed line) and those found experimentally (solid line, downward pointing peaks). 

Figure 1.5 Pd-catalyzed formation of indolinones (experiment, R = Cy, R = Bu) with selected key intermediates based on B3LYP calculations (R = Me, R = Me, relative free energies in kcalmoh ) [18].

Figure 15. Calculated potential energy surface and geometries of intermediates of the V" + CO2 reaction. The energy of the lowest energy state for the quintet (solid hnes) and triplet (dotted lines) stationary points are shown. Energies are calculated at the CCSD(T)/6-311+G(3df) level, at the B3LYP/6-311+G(d) geometry and include zero-point energy at the B3LYP/6-311+G(d) level.

A thorough computational study of this process has been carried out using B3LYP/ONIOM calculations.31 The rate-determining step is found to be the formation of the rhodium hydride intermediate. The barrier for this step is smaller for the minor complex than for the major one. Additional details on this study can be found at ... 

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