Binuclear Highly Distorted Iron(III) Porphyrins Bridged by the Dianions of Hydroquinones: Role of the Bridge in Electronic Communication

Abstract

A family of binuclear highly substituted and distorted ferric porphyrins bridged through a variety of p-hydroquinone dianions is reported. Two iron(II) porphyrins are oxidized with a consequence of 2 e reduction of the p-benzoquinone unit, which produces the binuclear ferric complex bridged with dianions of hydroquinone. The electronic structures of the dimeric complexes have been confirmed by using UV/Vis, IR, 1 H NMR, EPR and Mössbauer spectroscopy as well as single-crystal X-ray diffraction studies. The hydroquinone plane is remarkably tilted to form a Fe-O-C angle of approximately 132°and a dihedral angle of approximately 53°with the porphyrin mean plane. Variable-temperature magnetic susceptibility measurements

Nonplanar porphyrins: synthesis, properties, and unique functionalities

“…166 Metal complexes with the general MO(R)TPP substructure (R = Et, Pr, iPr, iBu) have been structurally characterized with M = 2H, 64b 3H, 167 4H, 155 P V , 168 V IV , 169 Fe III , 170 Co II , 171 Ni III , 172 Cu II , 173 Zn II , 63 Pd II , 66 and Sn IV , 174 each showing the familiar saddle shape. Similarly, crystal structures of OET(Ar)P with Ar: 175 2,6-diF-C 6 H 3 , 66 2,6-diCl-C 6 H 3 , 176 3,5-diMe-C 6 H 3 , 177 3,4,5-tri-MeO-C 6 H 2 , 178 and C 6 F 5 5b aryl units at C m -positions have been reported. The structural chemistry of these simple variants of the dodecasubstituted porphyrin molecules, while strongly deformed from regular chemical structure is remarkably self-similar.…”

“…Metal complexes with the general MO(R)TPP substructure (R = Et, Pr, iPr, iBu) have been structurally characterized with M = 2H, 64 b 3H, 167 4H, 155 P V , 168 V IV , 169 Fe III , 170 Co II , 171 Ni III , 172 Cu II , 173 Zn II , 63 Pd II , 66 and Sn IV , 174 each showing the familiar saddle shape. Similarly, crystal structures of OET(Ar)P with Ar: 2-NH 3 + C 6 H 4 , 67 a 4-HO-C 6 H 4 , 4-Me-C 6 H 4 , 171 4-F 3 C-C 6 H 4 , 171 4-MeO-C 6 H 4 , 175 4-NC-C 6 H 4 , 4-F-C 6 H 4 , 4-Cl-C 6 H 4 , 4-Br-C 6 H 4 , 66 4-MeO 2 C-C 6 H 4 , 175 2,6-diF-C 6 H 3 , 66 2,6-diCl-C 6 H 3 , 176 3,5-diMe-C 6 H 3 , 177 3,4,5-tri-MeO-C 6 H 2 , 178 and C 6 F 5 5 b aryl units at C m -positions have been reported.…”

From mononuclear iron phthalocyanines in catalysis to μ-nitrido diiron complexes and beyond

“…In contrast to µ-hydroxo counterparts [96], the Fe(III) sites in µ-fluoro species are equivalent. A family of bisporphyrins where two Fe(III) centers are bridged by the dianions of hydroquinones has been described [117].…”

Access to Corrole-Appended Persubstituted Benzofurans by a Multicomponent Reaction: The Dual Role of p-Chloranil

“…It is well-known that, due to its high electron affinity (first reduction potential of −0.42 V), p -chloranil (2,3,5,6-tetrachloro-1,4-benzoquinone) is a standard reagent, widely used as a stoichiometric oxidant. , Although ubiquitous in organic chemistry, examples of p -chloranil acting as a coupling reagent whose core is embedded in the final product are rather limited, encompassing photochemical transformations, − hydroquinone-bridged tripyrrins, and bis-porphyrins, as well as push–pull systems based on benzoquinones …”