Perturbed angular correlation studies of indium metalloporphyrin complexesa)

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Abstract
Electric field gradients (EFG) at the metal center were studied in seven chloroindium porphyrin complexes and in chloroindium phthalocyanine by the technique of perturbed angular correlation of gamma rays. These complexes were synthesized with the probe nucleus 111In for use in polycrystalline and solution sources. The magnitudes of the EFGs of the metalloporphyrins span a wide range and are shown to correlate with the electron donating properties of the peripheral substituents. For the phthalocyanine complex the derived EFG is quite large in spite of the electron withdrawing properties of the phthalocyanine ring. The porphyrin complexes all exhibited appreciable distributions in the magnitudes of the EFGs, which may be correlated with the deformable nature of the porphyrin macrocycle in contrast to the relatively planar, inflexible structure of the phthalocyanine ring which showed no such spread. The PAC spectra of metalloporphyrins dissolved in organic solvents exhibited two attenuation components, whose parameters were consistent with porphyrinproperties and provide evidence for metalloporphyrin aggregation.