Bridge-stacked polymeric structure of a fluorinated Ga(III) porphyrin deduced from a perturbed difference fourier analysis of EXAFS spectra

Goulon, J.; Friant, P.; Goulon-Gìnet, C.; Coutsolelos, Athanassios G.; Guilard, Roger

doi:10.1016/0301-0104(84)85012-0

Cited by 19 publications

(4 citation statements)

References 16 publications

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“…These changes due to reaction of Ga-H with ethylene were isolated, and a difference analysis was performed to verify the number of new M-C bonds (Supplementary Fig. 9, Supplementary Table 10) 31,[41][42][43][44] . For example, there are approximately 0.4 and 0.2 Ga-C and Zn-C bonds per metal ion, respectively, by alkylation of the hydrides.…”

Section: Resultsmentioning

confidence: 99%

Olefin oligomerization by main group Ga3+ and Zn2+ single site catalysts on SiO2

Libretto

Quigley

et al. 2021

Nat Commun

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In heterogeneous catalysis, olefin oligomerization is typically performed on immobilized transition metal ions, such as Ni2+ and Cr3+. Here we report that silica-supported, single site catalysts containing immobilized, main group Zn2+ and Ga3+ ion sites catalyze ethylene and propylene oligomerization to an equilibrium distribution of linear olefins with rates similar to that of Ni2+. The molecular weight distribution of products formed on Zn2+ is similar to Ni2+, while Ga3+ forms higher molecular weight olefins. In situ spectroscopic and computational studies suggest that oligomerization unexpectedly occurs by the Cossee-Arlman mechanism via metal hydride and metal alkyl intermediates formed during olefin insertion and β-hydride elimination elementary steps. Initiation of the catalytic cycle is proposed to occur by heterolytic C-H dissociation of ethylene, which occurs at about 250 °C where oligomerization is catalytically relevant. This work illuminates new chemistry for main group metal catalysts with potential for development of new oligomerization processes.

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Section: Resultsmentioning

confidence: 99%

Olefin oligomerization by main group Ga3+ and Zn2+ single site catalysts on SiO2

Libretto

Quigley

et al. 2021

Nat Commun

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“…Perturbed Difference EXAFS analyses play a central role in the present study. Such analyses have already been successfully used to solve in a reliable way a number of ill-conditioned problems in porphyrin chemistry. ,,− For the sake of brevity, we will only refer here to a recent review in which the method is discussed and illustrated with specific applications. Nevertheless, one should be aware that the method has practical implications regarding the selection of the reference compounds.…”

Section: Methodsmentioning

confidence: 99%

Structural Studies Using X-ray Absorption Spectroscopy of Intermediates Formed by Reaction of Ozone with Halogeno(dodecaphenylporphyrinato)manganese(III) Derivatives

et al. 2000

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Difference EXAFS and XANES studies at the Mn K-edge are reported which shed light on the mechanisms of activation of the title compounds by ozone. The reaction of ozone with either the chloro- or bromoporphyrinato Mn(III) derivatives yields the same intermediate in which the metal is in a formally tetravalent (IV) state. The coordination scheme includes the four equatorial pyrrolic nitrogen atoms of the porphyrin plus two ozone molecules arranged in a symmetrical configuration with respect to the porphyrin core. This geometry implies that the metal is shifted back into the mean plane of the porphyrin nitrogens. The Mn coordination with each ozone molecule results in two nonequivalent Mn···O distances: R(Mn···O1) = 2.09 ± 0.02 Å; R(Mn···O2) = 2.49 ± 0.05 Å. The second signal is assigned to a much weaker bond with an asymmetric (anharmonic) distribution of the (Mn···O2) distances. Whereas these intermediates have little or no catalytic activity regarding the epoxidation of olefins, catalytically active species were obtained when ozone reacts with the same precursors in an excess of pyridine. In the catalytically active species, the (Mn···O1) signal remains unaffected by the presence of pyridine whereas the (Mn···O2) signal is decreased by a factor of 2. Since there is no evidence of pyridine being coordinated to Mn, we suspect that pyridine is mediating a partial decomposition of one bound ozone molecule to release an active radical species. From Cl K-edge XAS studies performed on the chlorinated species treated with ozone and model compounds, we can definitely rule out the formation of chlorates or hypochlorite anions but both the XANES and EXAFS spectra show that Cl is oxidized during its substitution by ozone at the Mn site and could yield with ozone a covalent moiety Cl−O−O−O similar to the one which is presumed to form in the stratosphere by reaction of chlorine radicals with ozone. Some more speculative would be the formation of dimeric species in which a single Cl atom could bridge two ozone molecules. The radial distribution around Cl would then consist of two oxygen nearest neighbors at R(Cl···O1) = 1.69 ± 0.03 Å and four oxygen atoms at R(Cl···O2) = 2.20 ± 0.02 Å. This model is supported by ab initio MSW simulations of the XANES as well as by the EXAFS spectra.

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“…21 Moreover, a perturbed difference Fourier analysis of EXAFS spectra has shown that a fluorooctamethylporphyrinatogallium(III) derivative is a bridge-stacked polymer where a fluorine atom bridges two porphyrinic macrocycles. 22 Recently, particular interest was paid to the synthesis and evaluation of gallium and indium porphyrins for their use in biomedical imaging applications. 23,24 The stability of indium porphyrins makes them an attractive synthetic target to produce radiolabeled 111 In derivatives.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The photochemical oxidation of indium(III) porphyrins containing metal–sulfur bonds [InL(SR), with L = porphyrinate and R = alkyl or aryl] leads to sulfonato complexes that crystallize as 1D polymers . Moreover, a perturbed difference Fourier analysis of EXAFS spectra has shown that a fluorooctamethylporphyrinatogallium(III) derivative is a bridge-stacked polymer where a fluorine atom bridges two porphyrinic macrocycles …”

Section: Introductionmentioning

confidence: 99%

Gallium(III) and Indium(III) Complexes with meso-Monophosphorylated Porphyrins: Synthesis and Structure. A First Example of Dimers Formed by the Self-Assembly of meso-Porphyrinylphosphonic Acid Monoester

et al. 2017

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The synthesis and structural characterization, both in solution by means of H andP NMR and UV-vis spectroscopies and in the solid state by X-ray diffraction on single crystal, of a series of gallium(III) and indium(III) meso-mono(diethoxyphosphoryl)porphyrins bearing different peripheral substituents as well as the corresponding monoesters and phosphonic acids are reported. This work describes the first example of the X-ray structure of a self-assembled dimer formed via strong binding between the oxygen atom of the phosphonate substituent and the gallium(III) cations of adjacent porphyrin molecules [Ga-O = 1.9708(13) Å].

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Bridge-stacked polymeric structure of a fluorinated Ga(III) porphyrin deduced from a perturbed difference fourier analysis of EXAFS spectra

Cited by 19 publications

References 16 publications

Olefin oligomerization by main group Ga3+ and Zn2+ single site catalysts on SiO2

Olefin oligomerization by main group Ga3+ and Zn2+ single site catalysts on SiO2

Structural Studies Using X-ray Absorption Spectroscopy of Intermediates Formed by Reaction of Ozone with Halogeno(dodecaphenylporphyrinato)manganese(III) Derivatives

Gallium(III) and Indium(III) Complexes with meso-Monophosphorylated Porphyrins: Synthesis and Structure. A First Example of Dimers Formed by the Self-Assembly of meso-Porphyrinylphosphonic Acid Monoester

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