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

Walker, F. Ann; Licoccia, Silvia; Paolesse, Roberto

doi:10.1016/j.jinorgbio.2006.01.038

Cited by 86 publications

(86 citation statements)

References 99 publications

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“…Thus, for noninnocentc omplexes M[TpXPC],i nw hichT pXPC refers to a meso-tris(para-X-phenyl)corrole, the Soret maximum redshiftsf or increasingly electron-donating para substituents X on the meso-phenyl groups. [17][18][19][20][21][22][23] No such redshifts are observed for electronically innocent metallocorroles.…”

Section: Introductionmentioning

confidence: 99%

“…[6,7] The FeCl triarylcorroles provide another wellstudied example of ligand noninnocence and they mayb ed escribed as Fe III (S = 3/2)-corroleC 2À metalloradicals with an overall S = 1g round state. [17][18][19] The metal-ligand spin coupling is mediated by aF e(3d z2 )-corrole(p)o rbital interaction. Proton NMR spectroscopy,D FT,a nd high-level ab initio calculations, among other methods, provide strong evidence for this electronic-structural description.…”

Section: Introductionmentioning

confidence: 99%

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Ligand Noninnocence in Coinage Metal Corroles: A Silver Knife‐Edge

Thomas

Vázquez‐Lima

Fang

et al. 2015

Chemistry A European J

122

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A silver β-octabromo-meso-triarylcorrole has been found to exhibit a strongly saddled geometry, providing the first instance of a strongly saddled corrole complex involving a metal other than copper. The Soret maxima of the Ag octabromocorroles also redshift markedly in response to increasingly electron-donating para substituents on the meso-aryl groups. In both these respects, the Ag octabromocorroles differ from simple Ag triarylcorrole derivatives, which exhibit only mild saddling and substituent-insensitive Soret maxima. These results have been rationalized in terms of an innocent M(III)-corrole(3-) description for the simple Ag corroles and a noninnocent M(II)-corrole(·2-) description for the Ag octabromocorroles. In contrast, all copper corroles are thought to be noninnocent, while all gold corroles are innocent. Uniquely among metallocorroles, silver corroles thus seem poised on a knife-edge, so to speak, between innocent and noninnocent electronic structures and may tip either way, depending on the exact nature of the corrole ligand.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ligand Noninnocence in Coinage Metal Corroles: A Silver Knife‐Edge

Thomas

Vázquez‐Lima

Fang

et al. 2015

Chemistry A European J

122

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“…Experimental data exists for complexes 6 a-c, [16] 7 a-c, [17] and 8 a,b, [10e, 18] including the X-ray structures of 6 a-c and 8 a,b,…”

Section: Introductionmentioning

confidence: 99%

“…[17] This led to a consensus about the electronic structures of the phenyl-and oxo-ligated iron complexes: a low-spin iron(IV) (S Fe = 1) that is chelated by the closed-shell corrolato tri-anion and is further charge-balanced by the mono-anionic axial ligand. An identical view was first proposed for the chloro-ligated complex 6 a by Vogel and co-workers, [16] based on the observation of only two unpaired electrons (S t = 1, as expected for low-spin iron(IV)) by means of magnetic susceptibility measurements.…”

Section: Introductionmentioning

confidence: 99%

“…[17,19,20] The strongest experimental support for the ironA C H T U N G T R E N N U N G (III) corrole radical formulation in the case of the chloro-ligated [17b,c, 20b] However, this difference shows the same sign and approximately the same magnitude in a quintet chloro- Potentially, 13 C NMR spectroscopy could provide additional strong support for ligand radicals, since it also directly probes the spin populations at the ligand nuclei, in particular for the meso-carbon atoms in the substituted corrolate complexes 7 a-9 a. However, the signals of meso-carbon resonances were too broad to be detected due to unfavorable relaxation rates.…”

Section: Introductionmentioning

confidence: 99%

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The Electronic Structure of Iron Corroles: A Combined Experimental and Quantum Chemical Study

Tuttle

Bill

et al. 2008

Chemistry A European J

118

123

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There is a longstanding debate in the literature on the electronic structure of chloroiron corroles, especially for those containing the highly electron-withdrawing meso-tris(pentafluorophenyl)corrole (TPFC) ligand. Two alternative electronic structures were proposed for this and the related [FeCl(tdcc)] (TDCC=meso-tris(2,6-dichlorophenyl)corrole) complex, namely a high-valent ferryl species chelated by a trianionic corrolato ligand ([Fe(IV)(Cor)(3-)](+)) or an intermediate-spin (IS) ferric ion that is antiferromagnetically coupled to a dianionic pi-radical corrole ([Fe(III)(Cor)(.2-)](+)) yielding an overall triplet ground state. Two series of corrole-based iron complexes ([Fe(L)(Cor)], in which L=F, Cl, Br, I, and Cor=TPFC, TDCC) have been investigated by a combined experimental (Mössbauer spectroscopy) and computational (DFT) approach in order to differentiate between the two possible electronic-structure descriptions. The experimentally calibrated conclusions were reached by a detailed analysis of the Kohn-Sham solutions, which successfully reproduce the experimental structures and spectroscopic parameters: the electronic structures of [Fe(L)(Cor)] (L=F, Cl, Br, I, Cor=TPFC, TDCC) are best formulated as ([IS-Fe(III)(Cor)(.2-)](+)), similar to chloroiron corrole complexes containing electron-rich corrole ligands. The antiferromagnetic pathway is composed of singly occupied Fe d(z(2) ) and corrole a(2u)-like pi orbitals, with coupling constants that exceed those of analogous porphyrin systems by a factor of 2-3. In the corroles, the combination of lower symmetry, extra negative charge, and smaller cavity size (relative to the porphyrins) leads to exceptionally strong iron-corrole sigma bonds. Hence, the Fe d(x(2)-y(2) )-based molecular orbital is unavailable in the corrole complexes (contrary to the porphyrin case), and the local spin states are S(Fe)=3/2 in the corroles versus S(Fe)=5/2 in the porphyrins. The consequences of this qualitative difference are discussed for spin distributions and magnetic properties.

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Coordination Chemistry

Brothers

Ghosh

2022

Fundamentals of Porphyrin Chemistry

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

Cited by 86 publications

References 99 publications

Ligand Noninnocence in Coinage Metal Corroles: A Silver Knife‐Edge

Ligand Noninnocence in Coinage Metal Corroles: A Silver Knife‐Edge

The Electronic Structure of Iron Corroles: A Combined Experimental and Quantum Chemical Study

Coordination Chemistry

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