The electrochemical behaviour of the adducts Cr(TPP)·Cl·L, whereTPP = tetraphenylporphyrin;L = pyridine, 2-picoline, 2,6-lutidine, 4-cyanopyridine, morpholine or 4-picoline is reported and the relationship between reduction potentials, the electron band I transition and the binding energy of the Cr2p3/2 level examined.
Based on criteria for the differences in oxidation potentials determined in acetonitrile by cyclic voltammetry and reduction potentials determined inDMSO, it is concluded that the adducts behave as normal metalloporphyrins. Further, variations for the different adducts are attributed primarily to different inductive effects from the heterocyclic axial groups. The adduct formed from 2,6-lutidine, however, shows anomalous behaviour which is attributed to a marked steric effect between the ligand and the porphinato-nitrogen atoms.
Volume 135, 2023
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