Effect of Medium Basicity on the Coordination Kinetics of meso-Nitro-Substituted Derivatives of 5-Phenyl-β-Octaalkylporphine with Zinc Acetate

Resumo

The kinetics of formation of zinc complexes of 10,15-dinitro-5-phenyl-2,3,7,8,12,13,17,18-octamethylporphine, 10,15,20-trinitro-5-phenyl-2,3,7,8,12,13,17,18-octamethylporphine, and 10,15,20-trinitro-5-(4-nitro-phenyl)-2,3,7,8,12,13,17,18-octamethylporphine were studied spectrophotometrically at 288–308 K in Zn(OAc)₂–acetonitrile and Zn(OAc)₂–1,8-diazabicyclo[5.4.0]-undec-7-en–acetonitrile solutions with different basicities. The compounds under study were identified by electronic absorption, IR and ¹H NMR spectroscopies. An analysis of the effect of nitro groups on the kinetics of coordination of Zn(II) with the studied ligands showed that the changes in complexing properties of nitro derivatives of 5-phenyl-β-octaalkylporphine are related to the electron-withdrawing effect of NO₂ groups, to structural effects of distortion of the planar structure of the macrocycle, and to alteration of basicity of the reaction medium.