Electrically Conductive Metallomacrocyclic Assemblies. High-Resolution Solid-State NMR Spectroscopy as a Probe of Local Architecture and Electronic Structure in Phthalocyanine Molecular and Macromolecular “Metals”

This contribution reports a high-resolution solid-state CPMAS study of the low-dimensional phthalocyanine (Pc) conductors Ni(Pc)I, H₂(Pc)I, (X = BF₄, PF₆, 0.35), and (X = BF₄, PF₆, SbF₆, z 0.33), as well as of the precursors Ni(Pc), H₂(Pc), and For the partially oxidized materials, large, locally resolved ₁₃C-conduction electron Knight shifts with dispersions as large as 400 ppm and multiplicities in accord with crystallographic site symmetries are observed. By using Ni(Pc)I selectively labeled with ₁₃C at the 1,1’ skeletal positions and with ₂H at the 4,4’ hydrogen atom positions, along with dipole dephasing techniques, it is possible to completely and unambiguously assign the CPMAS spectrum. From this information is obtained a map of the conduction electron hyperfine interaction about the carbon framework of the macrocycle. In Ni(Pc)I, the ratios of the 1,1’ to the 2,2’ ₁₃C spin-lattice relaxation times conform approximately to the Korringa relationship at room temperature. For the partially oxidized phthalocyanine series as a whole, a linear relationship is observed between the individual 1,1’ and 2,2’ ₁₃C Knight shifts and the corresponding Pauli-like magnetic susceptibilities.