ИСТИНА

The description of catalytic activity of transition metal compounds is a difficult problem for chemical physics especially if comparison of different catalysts is necessary. The isomerization of quadricyclane to norbornadiene catalyzed by transition metal porphyrins is a challenge and incidentally a benchmark for various theories of catalysis. Active involvement of low-lying electronic states of a catalyst into modification of the potential energy surface is an essential feature of this catalytic reaction. We performed a detailed analysis of this process in the framework of the effective Hamiltonian approach adjusted for description of reaction centers. A qualitative explanation of comparative catalytic activity of Mn-phtalocyanine and Co-tetraphenylporphyrin is obtained from the analysis of local many-electron states of free catalysts and their complexes with the reactant. This picture is confirmed by the numerical analysis of potential energy profiles for the isomerization in the presence of a catalyst.