The report that the pi-cation radical complexes of 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrinates have a near degenerate (2)A(1u)/(2)A(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 pi-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)porphyrin reacts with thianthrenium perchlorate to give a beta-thianthrenium derivative. The zinc complex reacts with iodine/silver perchlorate yielding neutral beta-iodinated derivatives. We report the structure of the thianthrenium derivative [Cu(TCl2PPTh)]ClO4 and a symmetrically substituted beta-tetraiodo derivative [Zn(TCl2PPI4)]. Crystal data: [Zn(TCl2PP.)OClO3]. CH2Cl2. 2C(6)H(14), monoclinic, space group Cc, a = 12.516(2) Angstrom, b = 21.327(3) Angstrom, c = 22.764(3) Angstrom, beta = 98.281(13)degrees, V = 6012.8(16) Angstrom(3), Z = 4; [Cu(TCl2PPTh)]ClO4. CHCl3. C6H5CH3, orthorhombic, space group Pca2(1), a = 14.7625(18) Angstrom, b = 12.220(2) Angstrom, c = 33.672(5) Angstrom, V = 6074.6(16) Angstrom(3), Z = 4; [Zn(TCl2PPI4)(THF)(2)] . 2THF, triclinic, space group P (1) over bar, a = 9.941(2) Angstrom, b = 11.615(2) Angstrom, c = 14.340(3) Angstrom, alpha = 99.11(3)degrees, beta = 103.27(3)degrees, gamma = 106.61(3)degrees, V = 1499.1(5) Angstrom(3), Z = 1.