Structure and Apparent Reactivity of the π-Cation Radical Derivatives of Zinc and Copper 5,10,15,20-Tetra(2,6-dichlorophenyl)porphyrinate

The report that the π-cation radical complexes of 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrinates have a near degenerate ² A_1u/²A_2u ground state has led us to examine their molecular structures. We wished to explore whether this near degeneracy leads to unusual structural features, namely, an alternating bond distance pattern in the 16-membered ring. The X-ray structure of the zinc complex of 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrinate has a possible alternating bond distance pattern that could result from a pseudo-Jahn−Teller effect of coupled A_1u and the A_2u electronic states. In our attempts to prepare and crystallize additional π-cation radicals, we found an unusual reactivity at the molecular periphery of these porphyrin derivatives. The copper complex of 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrinate reacts with thianthrenium perchlorate to give a β-thianthrenium derivative. The zinc complex reacts with iodine/silver perchlorate yielding neutral β-iodinated derivatives. We report the structure of the thianthrenium derivative [Cu(TCl₂PPTh)]ClO₄ and a symmetrically substituted β-tetraiodo derivative [Zn(TCl₂PPI₄)]. Crystal data:  [Zn(TCl₂PP^•)OClO₃ ]·CH₂Cl₂·2C₆H₁₄, monoclinic, space group Cc, a = 12.516(2) Å, b = 21.327(3) Å, c = 22.764(3) Å, β = 98.281(13)°, V = 6012.8(16) ų, Z = 4; [Cu(TCl₂PPTh)]ClO₄·CHCl₃·C₆H₅CH₃, orthorhombic, space group Pca2₁, a = 14.7625(18) Å, b = 12.220(2) Å, c = 33.672(5) Å, V = 6074.6(16) ų, Z = 4; [Zn(TCl₂PPI₄)(THF)₂]·2THF, triclinic, space group P1̄, a = 9.941(2) Å, b = 11.615(2) Å, c = 14.340(3) Å, α = 99.11(3)°, β = 103.27(3)°, γ = 106.61(3)°, V = 1499.1(5) ų, Z = 1.