[摘要]：Several models for the porphyrin ring current effect are constructed based on a classical line current approxn. and their performances in reproducing the obsd. induced shifts of ligand protons in SnIV(porphyrin) dicarboxylate complexes are compared. A new model is selected and the diamagnetic ring current running on the inner 16p-electron circuit of the porphyrin is the main contributor together with a minor paratropic ring current on the outer 20p-electron circuit. Conformational analyses of bis(biphenyl carboxylate) complexes of SnIV(tetraphenylporphyrin) in soln. were carried out with this porphyrin ring current effect model.
