Young Ja Lee

Preparation and stuctural characterization of nitrosyl complexes of ferric porphyrinates

Abstract Nitrosyl complexes of ferric porphyrinates have been prepared by reaction of perchloratoporphinatoiron(III) complexess with nitric oxide. Two species have been structurally characterized: aquonitrosyl(meso-tetraphenylporphinato)iron(III) perchlorate, [Fe(TPP)(NO)(H2O)]ClO4, and nitrosyl(octaethylporphinato)iron(III) perchlorate, [Fe(OEP)(NO)]ClO4. Crystal data: [Fe(TPP)(NO)(H2O)]ClO4, monoclinic, a = 10.303(2) A, b = 8.124(2) A, c = 21.364(8) A, and β = 97.76(2)°, Z = 2, space group P21/n, 3999 observed data, R1 = 0.057, R2 = 0.079,all measurements at 96 K. [Fe(OEP)(NO)]ClO4, monoclinic, a = 12.890(2) A, b = 20.363(3) A, c = 14.969(2) A, and β = 95.48(2)°, Z = 4, space group P21/n, 5956 observed data, R1 = 0.058, R2 = 0.063, all measurements at 292 K. All complexes are low-spin {FeNO}6 species. [Fe(OEP)(NO)]ClO4 is the first five-coordinate low-spin ferric porphyrinate to be structurally characterized. The FeNO moiety is essentially linear in both species. For [Fe(TPP)(NO)(H2O)]ClO4, FeNp = 1.999(6) A, FeN(NO) = 1.652(5) A, and FeO = 2.001(5) A. For [Fe(OEP)(NO)]ClO4 (Fig. 1), FeNp = 1.994(1) A, FeN(NO) = 1.644(3) A; the iron(III) atom is displaced 0.29 A from the mean plane of the porphinato core. The structural parameters of both complexes are appropriate for low-spin ferric porphyrinates. [Fe(OEP)(NO)]ClO4 forms a remarkable π-π dimer in the solid state (Fig. 2). The two planar cores are parallel with an interplanar separation of only 3.36 A.