Second and Third Modes of Racemization

Both of the 1-ce cavities of A and B in the crystal 12, which is classified in the third mode, have large volume. Since the change of the cell dimensions was small, the rate constant was obtained from the intensity variation of reflections which should be zero after racemization due to the extinction rule (F(h01), h=odd). The 1-ce groups of A and B have enough volume for racemization and have nearly the equal size to each other. This may be a reason why both of the groups became the disordered racemates. 

Although the A and B cavities of 16 have small cavities, there are favorite conditions for 16 as follows two 1-ce groups of A and B contact with each other around a pseudo inversion center and the cyano and methyl groups weie exchanged in racemization, whereas the methyl group and hydrogen were exchanged in racemization of 12. Moreover, the two benzene solvate molecules per one complex may relax the crystal lattice. 

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