Dimerization energies

QTAM analysis of dimerization energies and densities in HOH-OH2 system... 

Dimerization energies in kcalmol 1, dipole moments in Debye, distances and bond lengths in A. 

The radical (4) appears to be a weakly associated dimer in the solid state according to CNDO-2 calculations. Orbitals of the two molecules interact forming common bonding and antibonding orbitals, hence the dimer is classified as a two-center, two-electron, h -k system (25). Thermodynamically the dimer (25) is more stable than the alternative structures in which the monomers are connected by a or N—N -bond. The dimerization energy for (25) seems to be not more... 

Similarly to imidazol-2-ylidene (IV), the calculated value for the energy of dimerization of Enders-type carbene VII is only 9.5 kcal/mol. " These remarkably small values, at least partially due to the loss of aromaticity in the carbene dimers IV 2 and VII 2, highlight the difficulty of dimerization of such carbenes. In contrast, in the case of the parent acyclic diaminocarbene IX, Heinemann and Thiel found a dimerization energy of 45 kcal/mol. This poses another question What is the value of the energy barrier for the dimerization Nowadays, the dimerization of singlet carbenes is believed to follow a nonleast motion pathway that involves the attack of the occupied in-plane ct lone pair of one singlet carbene center on the out-of-plane vacant orbital of a second carbene (Fig. 8.13). Calculations... 

In order to determine whether molecular orbital methods could be used to predict and explain preferences for cocrystalization analogous to that discussed above, we present here AMI calculations on the dimerization energies of variously substituted benzoic acids. 

TABLE 36. Summary of transition state energies (AE and AH ) and dimerization energies (AE and AH) (kcalmol-1) of the dimerization of germenes3... 

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