Coordination of N-Substituted Porphyrins with Simple and Chelate Zinc Salts in DMSO

The effect of peripheral substitution in the porphyrin macrocycle (₂OEtP, H₂TPP) of the nature of the N-substituent (X = Me, Ph) and of the anion in the salt solvate (A = ^–, NO₃^–, ^–) on the complexation of the N-substituted porphyrins with zinc salts in DMSO is studied. The positions of the bands in the electronic absorption spectrum of the (A)M(N-X)P metal complex were found to depend only slightly on the nature of the A anion in the composition of the coordination sphere of the complex. An inhibition of coordination of the N-substituted ₂TPP derivatives by zinc nitrate was discovered that is not typical of porphyrins proper. The type of hybridization of the substituted nitrogen atom in the porphyrin molecule is discussed. A mixed type of hybridization is suggested: the sp²- and p³-forms in the ligands and an almost complete transition to the p³ form in the N-substituted metal complexes.