Dimerization of metalloporphyrin .pi. cation radicals. Characterization of two novel dimers: [Zn(OEP.cntdot.)(OH2)]2(ClO4)2 and [Ni(OEP)]2(ClO4)2

Iron corrolates: Unambiguous chloroiron(III) (corrolate)2− π-cation radicals

“…Thus, for both reasons, as well as the lack of 14 N superhyperfine structure on the EPR signal, it is likely that this is the EPR signal of the p-cation radical of the corrolate. In fact, the authors know that the complex [Fe(NO)(OECorr)] + contains a p-cation radical, because the X-ray crystallographic characterization of this oxidized complex shows that the two corrole planes are very close to each other (3.21 Å ) [93] that appears to allow spin coupling between the two macrocycle radicals similar to what has been observed previously for octaethylporphyrin-metal pcation radicals [90,97,98]. This implies that the singly-oxidized corrole is best formulated as an iron(III) p-cation radical rather than an iron(IV) nitrosyl.…”

Structural deformations and bond length alternation in porphyrin π-cation radicals

“…The structure determination of the fZnOEP Á OH 2 g 2 2 dimer revealed an interesting bonding feature for this p-cation radical derivative that had not been previously observed [17,18]. In this derivative, the bond distance values in the inner 16-membered ring showed an unexpected alternating pattern.…”

“…The value in the zinc derivative is 31.3°. The possible importance of the twist angle was suggested by the next species characterized fNiOEP Á g 2 2 , as the perchlorate salt, which had a twist angle of 40.4°and did not show the alternating distance pattern [18]. The notion of the importance of the twist angle was further enhanced by the observation of the alternating pattern in fFeOEP Á Clg 2 2 , which also had the same twist angle as the zinc derivative.…”

“…The ®rst complex to be characterized was that of the [Zn(OEP á )(OH 2 )] + cation which formed the cofacial dimer fZnOEP Á OH 2 g 2 2 [17,18]. In this derivative, the two cores are completely overlapped with a very short separation between the two mean planes of 3.31 A Ê .…”

Explorations in metalloporphyrin stereochemistry, physical properties and beyond

“…Further, I would take notice of two bodies of work that have not been discussed in this paper, work on the other oxynitrogen-ligated porphyrins (the ligands NO 2 − and NO 3 − ) [112][113][114][115][116][117][118][119][120][121][122][123][124] and the work on the characterization of π-cation radical complexes [125][126][127][128][129][130][131][132][133][134][135][136][137][138][139]. Diagram Illustrating the effect of axial ligand orientation on the axial bond distances in iron (III) species.…”