Complex formation of halogen substituted tetraphenylporphyrins and Cd(II)-tetraphenylporphyrins with MnCl2 in DMF

Abstract

Reactions of complex formation of 5,10,15,20-tetra-(2,6-dichlorophenyl)porphyrin, 5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin and metal exchange of their cadmium complexes with manganese chloride(II) in dimethylformamide were investigated. ortho -Substituted manganese complexes were synthesized by prolonged refluxing of the corresponding porphyrins with an excess of MnCl2 in dimethylformamide. Using the metal exchange reaction of Cd(II)-5,10,15,20-tetra-(2,6-dichlorophenyl)porphyrin and Cd(II)-5,10,15,20-tetra-(2,6-difluorophenyl) porphyrin, the corresponding Mn(III)-tetraphenylporphyrins were obtained. On the contrary, the coordination reactions of porphyrins substituted at the pyrrole and phenyl rings with manganese chloride in dimethylformamide proceed under mild conditions with the formation of complexes Mn(II)-2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra-(2,6-dichlorophenyl)porphyrin [the compound oxidizes in air to a mixture of Mn(II) and Mn(III)-porphyrins] and Mn(II)-2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin. The synthesized compounds were identified using UV-Vis, 1H NMR spectroscopy and mass-spectrometry. Metal exchange reaction of ortho -substituted Cd(II)-porphyrins and complex formation of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra-(2,6-dichlorophenyl)porphyrin with manganese chloride in dimethylformamide were studied by the spectrophotometric method. The kinetic parameters of the reactions were calculated. A strong effect of β- and ortho -substitution on the reactions of complex formation and metal exchange of the studied compounds was found.