The crystal and mol. structures of OEP(NO2)4 and its Zn complexes OEP(NO2)2Zn complex, where OEP is octaethylporphine, were determine by x-ray diffractometry. Both compounds have space group P21/n, with a 1.052(5), b 20522(1), c 1.356(7) nm, b 96.12?for OEP(NO2)4; and a 0.4890(2), b 2.1816(13), c 1.5039(9)nm, b 95.24? The structures of porphinate skeleton with or without the central Zn(II) were compared. The configuration of nitro groups on the porphine skeleton show that these nitro groups also participate in the conjugation of the porphine in different levels.

Key words: CRYSTAL STRUCTURE DETERMINATION, NITRO GROUP, ZINC COMPLEX, MOLECULAR STRUCTURE, X-RAY DIFFRACTION ANALYSIS, STRUCTURAL ANALYSIS, SUBSTITUENT EFFECT, PORPHYRIN