Metal Complexes of Dioxo-porphyrins-Zinc(II) Complexes of 2,3,7,8,12,13,17,18-Octaethyl-5,15-dioxo-porphyrin and 5,15-Dioxo-etioporphyrin I

The crystal structures of two zinc(II) 5,15-dioxo-porphyrins (porphodimethenes) have been determined to investigate the coordination chemistry of porphyrins with interrupted conjuga­ tion system. Both compounds have a five-coordinated zinc center with pyridine as axial ligand and show overall structural parameters very similar to porphyrins. The oxidized meso-posi­ tions are, however, easily identified by longer CmC a bond lengths and smaller CaC mC a angles. The macrocycles exhibit a small degree of conformational distortion, and the etioporphyrin I derivative shows evidence for ^-stacking in the crystal. Crystal data: 1 C41H47N 50 2Zn. Triclinic, a = 10.052(3) Ä, b = 14.139(4) Ä, c = 14.635(5) A, a = 105.17(2)°, ß = 108.62(3)°, y = 106.29(2)°, V = 1745.3(9) Ä3, CuKa radiation, X = 1.54178 Ä, space group P I, Z = 2 R = 0.089. 2 C37H39N 50 ,Z n . Triclinic, a = 12.122(3) Ä, b = 12.383(3) A, c = 12.759(4) A, a = 61.77(2)°, ß = 72.19(2)°, y = 70.32(2)°, V = 1563.8(8) Ä3, CuKa radiation, X = 1.54178 A, space group P 1, Z = 2, R = 0.076.