Structural study of a manganese(II) `picket-fence' porphyrin complex

Abstract

`Picket-fence' porphyrin compounds are used in the investigation of interactions of hemes with dioxygen, carbon monoxide, nitric monoxide and imidazole ligands. (Cryptand-222)potassium chlorido[meso-tetra(α,α,α,α-o-pivalamidophenyl)porphyrinato]manganese tetrahydrofuran monosolvate (cryptand-222 is 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane), [K(C18H36N2O6)][Mn(C64H64N8O4)Cl]·C4H8O or [K(222)][Mn(TpivPP)Cl]·THF [systematic name for TpivPP: 5,10,15,20-tetrakis(2-tert-butanamidophenyl)porphyrin], is a five-coordinate high-spin manganese(II) picket-fence porphyrin complex. It crystallizes with a potassium cation chelated inside a cryptand-222 molecule; the average K—O and K—N distances are 2.83 (4) and 2.995 (13) Å, respectively. All four protectingtert-butyl pickets of the porphyrin are ordered. The porphyrin plane is nearly planar, as indicated by the atomic displacements and the dihedral angles between the mean planes of the pyrrole rings and the 24-atom mean plane. The axial chloride ligand is located inside the molecular cavity on the hindered porphyrin side and the Mn—Cl bond is tilted slightly off the normal to the porphyrin plane by 3.68 (2)°. The out-of-plane displacement of the metal centre relative to the 24-atom mean plane (Δ24) is 0.7013 (4) Å, indicating a noticeable porphyrin core doming.