Carrier Properties of Porphyrinic Molecular Metals

Abstract

A series of quasi one-dimensional molecular metals based on metallomacrocycle building blocks is compared. The group of compounds Ni(L)I, where L = dian-ion of phthalocyanine (PC), tetrabenzporphyrin (TBP), or triazatetrabenzporphyrin (TATBP), are isoionic and isostructural but the nature of the charge carrier is quite different in each material. Oxidation in Ni(PC)l is exclusively from ligand π-orbitals so that conduction is associated with delocalized π-orbitals. Ni(TBP)I and Ni(TATBP)I display epr spectra that demonstrate that oxidation has occurred from both ligand ir-orbitals and Ni d-orbitals so that these compounds display a novel, doubly mixed-valence state. The compounds Ni(PC)I, Ni(TMP)I, and Ni(OMTBP)I (TMP = tetramethylporphyrin, OMTBP = octamethyltetrabenzporphyrin) form an isoionic series where Coulomb correlations are of progressively greater importance.