Synthesis of electron-deficient fluorinated porphyrins through scrambling: Characterization and quantitative crystal structure analysis

MacDonald type 2 + 2 condensation of 5-(4-cyanophenyl)dipyrromethane with pentafluorobenzaldehyde in presence of BF3 center dot OEt2 results in unexpected formation of fluorinated porphyrins namely, B-4, H2T(PFP)P, 1; AB(3), H2T(PFP)(CP)P, 2; cis-A(2)B(2), cis-H2B(PFP)B(CP)P, 3 and A(3)B, H-2(PFP)T(CP)P, 5 in addition to the expected trans-A(2)B(2), trans-H2B(PFP)B(CP)P, 4 porphyrin through scrambling of the 4-cyano/pentafluoro phenyl substituents. The same reaction in TFA catalyst leads to non-scrambling condition and yields trans-A(2)B(2) porphyrin. The complementary reactions were also performed using 5(pentafluorophenyl)dipyrromethane to analyze the level of scrambling. The copper complexes of 3 and 5 have been structurally characterized by single crystal X-ray diffraction analysis and the role of weak intermolecular interactions in their crystal packing has been analyzed and quantified using Hirshfeld surface analysis. (C) 2014 Elsevier B.V. All rights reserved.