Studies on Organic Fluorine Compounds. XXI. Isomerization of Fluorinated Dewar Pyridine Derivative and Its Metal Complexes

Abstract

Kinetic studies were made on the thermal isomerization of 2, 4, 6-trimethyl-3, 5-bis (trifluoromethyl)-1-azabicyclo [2. 2. 0] hexa-2, 5-diene (I) to 2, 4, 6-trimethyl-3, 5-bis (trifluoromethyl)-pyridine (II), M (I)₂Cl₂ (M=Pd^II and Pt^II) to M (II)₂Cl₂, and M (I). (II) Cl₂ to M (II)₂Cl₂ The isomerization of I or I moiety of metal complexes to II or II moiety, respectively, was found to be first-order in various solvents. Mechanism of isomerization was discussed and was suggested to be a symmetry forbidden state-conservative concerted mechanism facilitated through configuration interaction, or a process through recombination of two skewed allyl radical parts. The isomerization I→II was facilitated by the presence of strong acids or Lewis acids and this isomerization catalyzed by acids seems to pass through the ionic mechanism.