NMR Studies of Paramagnetic Metallocarbaporphyrinoids

Pacholska‐Dudziak, Ewa; Latos‐Grażyński, Lechosław

doi:10.1002/ejic.200700078

Cited by 23 publications

(17 citation statements)

References 110 publications

(114 reference statements)

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“…1 H NMR spectroscopy was shown to be a uniquely definitive method for detecting and characterizing paramagnetic metalloporphyrinoids − and can be applied as a definitive probe for detecting metal–arene interaction in benziporphyrins. ,, It was shown that, depending on axial ligation, the one-electron oxidation of ruthenium porphyrins afforded ruthenium(II) porphyrin π-cation radicals or ruthenium(III) porphyrins. ,− In the second case, two fundamental (d xy ) 2 (d xz d yz ) 3 or less-common (d xy ) 1 (d xz d yz ) 4 electronic structures are possible, distinguished by the distribution of an unpaired electron on d orbitals to be directly correlated with the diagnostic pattern of paramagnetically shifted 1 H NMR resonances.…”

Section: Resultsmentioning

confidence: 99%

“…One has to be aware of the fact that the organometallic chemistry of paramagnetic metallocarbaporphyrinoids has been focused on a rather limited number of transition-metal ions [copper(II), iron(II,III), and nickel(I,II)]. The selected ligands such as N-confused porphyrin, O-confused porphyrin, m -benziporphyrin, N-confused pyriporphyrin, vacataporphyrin, ethyneporphyrin, and p -benziporphyrin provided the appropriate macrocyclic environment. ,, …”

Section: Introductionmentioning

confidence: 99%

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Ruthenium(II) and Ruthenium(III) Complexes of p-Benziporphyrin: Merging Equatorial and Axial Organometallic Coordination

2017

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A diamagnetic ruthenium(II) complex of 5,10,15,20-tetraphenyl-p-benziporphyrin [Ru(p-BzP)(CO)Cl] was obtained via the insertion of ruthenium into p-benziporphyrin using triruthenium(0) dodecacarbonyl [Ru(CO)] as the metal source. The procedure applying dichloro(cycloocta-1,5-diene)ruthenium(II) (polymer, [Ru(COD)Cl]) afforded the paramagnetic six-coordinate ruthenium(III) p-benziporphyrin [Ru(p-BzP)Cl]. As shown by X-ray crystallography, the p-phenylene ring in both complexes is sharply tilted out of the N plane, as reflected by the respective N (pyrrole)-C (p-phenylene) dihedral angle [Ru(p-BzP)(CO)Cl, 52.5°; Ru(p-BzP)Cl, 53.7°]. p-Phenylene is bound to the ruthenium cation in an η fashion, revealing the shortest ever Ru-C distance in the series of p-benziporphyrin complexes [Ru(p-BzP)(CO)Cl, 2.275(2) Å; Ru(p-BzP)Cl, 2.324(5) Å]. The reaction of Ru(p-BzP)(CO)Cl with ArMgCl or AlkMgCl results in the formation of diamagnetic six-coordinate ruthenium(II) p-benziporphyrin complexes containing the apically coordinated σ-alkyl or σ-aryl ligands, where the metal ion simultaneously coordinates to three carbon centers respectively accommodating η (phenylene) and σ (aryl and alkyl) modes. Reactions of σ-aryl (alkyl) carbanions with paramagnetic Ru(p-BzP)Cl have been followed by H NMR spectroscopy. The procedure afforded the six-coordinate paramagnetic ruthenium(III) p-benziporphyrin [Ru(p-BzP)(Ph)Cl], which binds one σ-aryl ligand, as reflected by the characteristic H NMR spectra spread within the +120 to -120 ppm range. Both paramagnetic complexes Ru(p-BzP)(Ph)Cl and Ru(p-BzP)(p-Tol)Cl are formed as a mixture of two stereoisomers differentiated by two nonequivalent locations of σ-aryl with respect to the puckered macrocyclic ring. The paramagnetic shifts of σ-aryls are indicative of π-spin delocalization patterns. Analysis of the contact shifts and parallel density functional theory calculations of the spin density distribution in Ru(p-BzP)Cl, Ru(p-BzP)(Ar)Cl, and Ru(p-BzP)(Alk)Cl reflect the features of the d(dd) electronic ground state.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ruthenium(II) and Ruthenium(III) Complexes of p-Benziporphyrin: Merging Equatorial and Axial Organometallic Coordination

2017

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“…N-Confused pyriporphyrin 472b afforded an iron(II) complex 476 , and this reacted with molecular oxygen to give an oxygen-bridged iron(III) complex 477 (Scheme ). , …”

Section: Benziporphyrins Heterobenziporphyrins and Related Systemsmentioning

confidence: 99%

Carbaporphyrinoid Systems

2016

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Following immediately after the serendipitous discovery of N-confused porphyrins, remarkably diverse carbaporphyrinoid systems have been synthesized and investigated. By replacing a pyrrolic unit within the porphyrin framework with cyclopentadiene, indene, azulene, cycloheptatriene, or benzene, new families of porphyrin-like macrocycles were produced. True carbaporphyrins are fully aromatic structures, while benziporphyrins are essentially devoid of macrocyclic aromatic character, and azuliporphyrins fall midway between the two extremes. Monocarbaporphyrinoids are superior organometallic ligands and form stable complexes with copper(III), silver(III), gold(III), nickel(II), palladium(II), platinum(II), rhodium(III), iridium(III), and ruthenium(II). Unusual oxidation reactions have also been discovered, commonly leading to derivatization of the internal carbon atom. In addition, structural rearrangements have been uncovered that allow the conversion of azuliporphyrins into benzocarbaporphyrins, and benziporphyrins into carbaporphyrins. Although less well studied, many examples of dicarbaporphyrinoids have been reported, and these show equally intriguing characteristics. Furthermore, contracted and expanded carbaporphyrinoids have been investigated. Studies in this area provide fundamental insights into the aromatic properties, tautomerization, and reactivity of porphyrins and related macrocyclic systems.

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“…Since brief reviews on porphyrin analogues including NCPs and expanded porphyrins are already reported, this review especially focuses on the recent development in the chemistry of NCP, NFP and related compounds. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] The evolutionary tree of the porphyrin family relevant to confusion is summarized in Chart 1. Although carbaporphyrins, heteroporphyrins and hetero-confused porphyrins are obviously important and interesting members of the porphyrin family, they are not mentioned here because of space considerations.…”

Section: Introductionmentioning

confidence: 99%

Blooming of confused porphyrinoids—fusion, expansion, contraction, and more confusion

2012

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This article introduces an overview of progressively developing chemistry of N-confused porphyrin and related macrocycles. Study on confusion results in discovery of fusion and combination with expansion or contraction has provided uniquely important classes of porphyrinoids. Syntheses, properties and coordination chemistry of such porphyrinoids are briefly described. Possibilities in applications are also mentioned.

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NMR Studies of Paramagnetic Metallocarbaporphyrinoids

Cited by 23 publications

References 110 publications

Ruthenium(II) and Ruthenium(III) Complexes of p-Benziporphyrin: Merging Equatorial and Axial Organometallic Coordination

Ruthenium(II) and Ruthenium(III) Complexes of p-Benziporphyrin: Merging Equatorial and Axial Organometallic Coordination

Carbaporphyrinoid Systems

Blooming of confused porphyrinoids—fusion, expansion, contraction, and more confusion

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