STABILITY CONSTANTS AND PROTON MAGNETIC RESONANCE STUDIES OF ZINC ALPHA,BETA,GAMMA,DELTA-TETRAPHENYLPORPHIN AND SUBSTITUTED PYRIDINES

The equilibrium constants of ten substituted pyridine derivatives with zinc α,β,γ,δ-tetraphenylporphin have been measured in benzene at 25°. Only 1:1 complexes are observed. In contrast to iron(II) and magnesium(II) porphyrins, the stability constants parallel the ligand basicity. A linear log K-pK correlation and a Hammett plot with p = +1.50 was obtained. Proton magnetic resonance studies indicated that the exchange between the coordinated and uncoordinated pyridine was rapid at -60° and that the structures of the zinc(II) and magnesium(II) monopyridinates are similar. © 1969, American Chemical Society. All rights reserved.