Conformational distortions of π-cation radical (β-oxoporphyrin)copper(II) derivatives: [Cu(2,7,12-trioxoOEHP^·)][SbCl₆] and [Cu(2,7-dioxoOEiBC^·)][SbCl₆]

Abstract

The preparation and characterization of two π-cation radical derivatives of copper β-oxo porphyrins is described. [3,3,8,8,13,13,17,18-Octaethyl-(3H,8H,13H)-porphine-2,7,12-trionato (2-)] copper π-cation radical, [Cu(2,7,12-trioxoOEHP.)]+, and [3,3,8,8,12,13,17,18-octaethyl-(3H,8H)-porphine-2,7-dionato(2-)] copper π-cation radical, [Cu(2,7-dioxoOEiBC.)]+, have been prepared and characterized by single-crystal X-ray determinations, UV/vis/NIR, and IR spectroscopies. Both molecules have modest distortion from the planarity and show monomeric units in the solid state. [Cu(2,7-dioxoOEiBC.)]+ shows a concentration dependent near-IR band at 1410 nm. Crystal data for [Cu(2,7,12-trioxoOEHP.)][SbCl6]: tetragonal, space group P42/n, a = 31.085 (14) Å, c = 9.410 (4) Å, V = 9093 Å3, Z = 8, T = 127 K. Crystal data for [Cu(2,7-dioxoOEiBC.)][SbCl6]: monoclinic, space group P21/n, a = 9.655 (4) Å, b = 20.592 (8) Å, c = 43.347 (17) Åβ = 89.97(1)°, V = 8618. Å3, Z = 8, T = 100 K.

Metalloporphyrin Mixed-Valence π-Cation Radicals: [Fe(oxoOEC•/2)(Cl)]2SbCl6, Structure, Magnetic Properties, and Near-IR Spectra

“…The equatorial Fe–N bond distances range from 2.047(8) to 2.124(8) Å; there are two types of Fe–N bond distances as observed in [Fe(oxoOEC)(Cl)], [Fe(oxoOEC • )(Cl)]SbCl 6 , and other metal β-oxoporphyrins. − The metal to nitrogen distance is longer to the pyrrolinone ring than that to the pyrroles: Fe–N(2) = 2.124(8) Å vs the averaged Fe–N p distance = 2.060(18) Å, comparable to those found in [Fe(oxoOEC)(Cl)] 2.125(5) Å vs 2.061(5) Å) and [Fe(oxoOEC • )(Cl)]SbCl 6 (2.106(6) Å vs 2.052(7) Å). Differences between the three species appear to be a consequence of differences in the macrocyclic conformation.…”

Photophysical Exploration of Two Isomers of Octaethyltrioxopyrrocorphin

“…Among the β-oxoporphyrinoids, the triketones stand out as the least studied compound class. The nickel and copper complexes of the isomeric trioxopyrrocorphins 3-O 2,7,12 or 3-O 2,7,18 were prepared, and their structure, axial binding properties, and electrochemical properties were studied. ,,, We recently described the preparation of the hitherto unknown regioisomers of the triketones and revealed their unique electronic properties. , They are, against expectations for regular pyrrocorphins, aromatic, with the regioisomers varying significantly in their degree of aromaticity. As a reduction of one or two oxo-groups led to a degradation of the aromaticity, the aromatic nature of the trioxopyrrocorphins could be unambiguously linked to the presence of the β-oxo-substituents …”