Spirodiporphyrins—As Binuclear Metal Complexes

Abstract

Dedicated to Professor Ronald BreslowPorphyrin supermolecules constructed from multiple porphyrin moieties that are linked covalently [1] or coordinatively [2] by spacers have developed as an important line of research in porphyrin chemistry (with potential applications as electronic or optical functional units, sensors, and artificial photosynthetic devices). In contrast to these porphyrin supermolecules, the no less intriguing di-and oligoporphyrins devoid of spacers, that is, meso-meso-, b-b-or meso-b-linked porphyrins, have only recently attracted attention (Scheme 1).Among the diporphyrins of this type, the meso-mesodiporphyrin 1 (n = 1) [3]

Metamorphosis of Tetrapyrrole Macrocycles

“…Support for this mechanism comes from the behavior of bimetallic [36]octaphyrin(1.1.1.1.1.1.1.1), which splits into the two porphyrin macrocycles via the covalently linked spiro intermediates 13 (Scheme 3). [7,8] predominating at room temperature, and the equilibrium can be shifted photochemically to 11. [7] Osuka and co-workers discovered the ultimate transformation of the copper(II) complex of an octaphyrin into the corresponding spirocyclobutane intermediate 14, which was split into two porphyrin molecules 15 through a cycloreversion reaction (Scheme 4).…”

“…[7,8] predominating at room temperature, and the equilibrium can be shifted photochemically to 11. [7] Osuka and co-workers discovered the ultimate transformation of the copper(II) complex of an octaphyrin into the corresponding spirocyclobutane intermediate 14, which was split into two porphyrin molecules 15 through a cycloreversion reaction (Scheme 4). [8,9] Although the formation of spiro compounds has so far only been experimentally observed for metal complexes, the close analogy between these reactions indicates the likelihood of their involvement in the reaction 8!9 as well.…”

“…A notable exception was the finding that metal complexes of some octaphyrins [4] can undergo a thermal transformation into spirodicorroles 4. [7] Some of these compounds can be split into two porphyrins in which the expanded porphyrins are linked with "regular" tetrapyrroles. [8,9] In a recent paper by Gros et al, an intriguing observation was made that further links the different classes of polypyrrolic classes.…”

Extrusion of Boron(III) Subporphyrin from meso‐Heptakis(pentafluorophenyl)[32]heptaphyrin upon Cooperative CuII and BIII Metalation

“…Thus, we examined the metalation of 1 at the semiporphyrin-like pocket by treating 1 with a solution of Zn(OAc) 2 + : m/z 1767.0194) in its high-resolution electrospray ionization (HR-ESI) mass spectrum, and it exhibits a simple 1 H NMR spectrum that reveals its C 2 -symmetric structure in solution (Supporting Information).…”

Dicopper and Disilver Complexes of Octaphyrin(1.1.1.1.1.1.1.1): Reversible Hydrolytic Cleavage of the Pyrrolic Ring to a Keto–Imine

“…[4] Vogel et al revealed an interesting equilibrium of the dipalladium complex of octaphyrin(1.1.1.0.1.1.1.0) and its bis-spiro derivative, and isolated the dinickel complex of a spirodicorrole upon metalation of dioxooctaphyrin(1.1.1.0.1.1.1.0). [5] Both processes involved large skeletal rearrangements. We also reported that complexation of [36]octaphyrin(1.1.1.1.1.1.1.1) 1 with copper provided the dicopper(ii) complex 2, which underwent a quantitative thermal splitting reaction into two copper(ii) porphyrins, 3, through an unprecedented metathesis that involved the scission and formation of at least two carbon-carbon bonds.…”