Reaction path intuitive

Let us discuss now the most important conclusions that can be deduced from these figures. First, the most important conclusion concerns the comparison of the values of functional L along the optimal allowed and forbidden reaction paths. As can be seen, the value for the allowed conrotatory cyclisation is lower in absolute value than in the forbidden one. This confirms the intuitive expectation of the least motion principle that the extent of electron reorganisation should be smaller in allowed reactions than in the forbidden ones. On the basis of this primary test of reliability of the proposed model it is, in the next step, possible to start with the analysis and the classification of the reaction mechanisms for both individual reactions. Especially interesting in this connection is again the thermally forbidden disrotatory cyclisation. The reason for this... 

Differently from the previous case (CO-Mb), the reaction path associated to such a tautomeric process may be less intuitive. For this reason we calculated the intrinsic reaction coordinate (IRC) [61] in vacuum which provided a linear generalized degree... 

Although this type of reaction path corresponds well to chemical intuition, it suffers from a serious drawback the reaction path from reactants to products generally differs from the path in the opposite direction, i.e., chemical hysteresis may take place (127). A saddle point can be reached only in a favorable case. Moreover, it is an expensive procedure because the system under study must be reoptimized in each step. 

Nevertheless, when properly used, the intuitive reaction path represents a useful tool for investigating reaction mechanisms, especially in connection with semiempirical methods of quantum chemistry. 

MINDO/3//MINDO/3 Water migration from Nu to L, intuitive reaction path (177)... 

M1NDO/3//M1NDO/3 Study of reactivity and selectivity, intuitive reaction path (179)... 

How the reactivity of a particular site changes during a chemical reaction has been studied [152], Ab initio SCF calculations [152] of condensed Fukui functions at various sites at different stages of a dissociation reaction have been performed. The variation of these reactivity indices along the reaction path is consistent with chemical intuition. 

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