Wydział Chemii

Radomir Myśliborski

Krystyna Rachlewicz

Lechosław Latos-Grażyński

2007

Journal of Porphyrins and Phthalocyanines

11

172-180

10.1142/S1088424607000229

Naukowa

Angielski

Artykuł

Oxidation of (PyPH)Fe^IIBr, an iron(II) complex of 6,11,16,21-tetraaryl-3-aza-m-benziporphyrin (N-confused pyriporphyrin, (PyPH)H) has been followed, in the presence of pyridine, by ¹H and ²H NMR spectroscopy. One-electron oxidation with dioxygen, accompanied by deprotonation of a C(22)H fragment and formation of a Fe-C(22) bond, produced a low-spin, six-coordinate iron(III) complex [(PyP)Fe^III(py)₂]⁺ as confirmed by combination of ¹H NMR, EPR and structural data. The characteristic patterns of ¹H NMR pyrrole and meso-aryl resonances resemble features assigned to the less common, low-spin ground electronic state ((d_xzd_yz)⁴(d_xy)¹) of iron(III) regular porphyrins. A conformational rearrangement process has been detected which involves two structures differentiated by macrocyclic ruffling. The structure of {H[(PyP)Fe^III(py)₂]₂}(Fe^IIIBr₄)₃·CH₂Cl₂ has been determined by X-ray crystallography. The cationic complex involves a six-coordinate iron atom bound to the N-confused pyriporphyrin through its three nitrogens (Fe-N(23) = 1.924(7), Fe-N(24) = 1.979(7), Fe-N(25) = 1.9343(7) Å) and the pirydyl trigonal C(22) atom (Fe(1)-C(22) = 1.972(10) Å). The porphyrin is strongly ruffled, defining two deep grooves along C_meso-C_meso axes at right angles to each other. Two axial pyridine ligands are located in the prearranged equatorial ligand grooves. The iron lies in the N₃C plane of the macrocycle defined by coordinating nitrogen and carbon atoms. In the solid, pairs of molecules are positioned along the line defined by Fe(1)-C(22) and Fe(2)-C(91) bonds. The structure demonstrates the head-to-head arrangement of two [(PyP)Fe^III(py)₂]⁺ subunits revealing the adjacency of the two perimeter nitrogen atoms (the N(3)⋯N(72) distance = 2.587(10) Å) linked by the N⋯H⋯N hydrogen bond.

Carbaporphyrinoids, Core-modified porphyrin, Iron porphyrin, Pyriporphyrin

https://doi.org/10.1142/S1088424607000229