Effects of the ligands on the electrochemical oxidation of (benzylydeneacetone)Fe(CO)2L, with L=CO, phosphines and phosphites

Vichi, Eduardo J. S.; Stein, Edison

doi:10.1016/s0020-1693(02)00852-6

Cited by 7 publications

(4 citation statements)

References 15 publications

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“…By varying the substituents on the aryl ring connected directly to the enone π-system of the chalcone, both the inductive and mesomeric effects of the substituents may be probed. As the complexes [Fe(CO) 2 L(η 4 -PhCHCH−C{Me}O)] (L = phosphorus-containing ligand) have been used to explore the effect of the phosphorus ligands on metal−ligand binding and redox chemistry, we reasoned that these species would be a good framework to test our hypothesis. Species such as [Fe(CO) 3 (η 4 -PhCHCH−C{Me}O)] have been used as transfer reagents for the Fe(CO) 3 group, and a precise understanding of metal−ligand bonding might enable the design of ligands that will act as better leaving groups .…”

Section: Introductionmentioning

confidence: 99%

A Rationale for the Linear Correlation of Aryl Substituent Effects in Iron(0) Tricarbonyl Complexes Containing α,β-Unsaturated Enone (Chalcone) Ligands

et al. 2007

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A library of iron(0) tricarbonyl complexes containing η4-bound α,β-unsaturated enone ligands [Fe(CO)3(η4-RCHCH−C{Ph}O)] has been prepared to facilitate comprehensive correlation of the electronic withdrawing/donating properties of the substituent, R, with the strength of the metal−ligand interaction. The IR and NMR spectroscopic data proved invaluable in aiding a comprehensive correlation and global understanding of the aryl substituent effects. The frequency of the M−CO bands in the infrared spectra of these species exhibits a linear correlation with the Hammett parameters for the substituents. The coordination shifts in both the 1H and 13C NMR spectra for the ligands exhibit a similar linear relationship. The largest coordination shifts are observed when more electron-withdrawing groups are present, implying that the organic ligand is primarily acting as a π-acid. The structures of six complexes of this type have been determined by single-crystal X-ray diffraction.

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Section: Introductionmentioning

confidence: 99%

A Rationale for the Linear Correlation of Aryl Substituent Effects in Iron(0) Tricarbonyl Complexes Containing α,β-Unsaturated Enone (Chalcone) Ligands

et al. 2007

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“…It has been suggested the isomer shifts of the iron will decrease both with an increase in ligand σ donation and iron π-back-donation to the ligand . For the entire temperature range, the IS of [Fe(TPP) (CCl 2 )] are approximately half those of [Fe(TFPP) (CPh 2 )], which suggests the CCl 2 bonds more strongly to iron than does the CPh 2 .…”

mentioning

confidence: 99%

Electronic Configuration and Ligand Nature of Five-Coordinate Iron Porphyrin Carbene Complexes: An Experimental Study

Liu

Zhang

et al. 2017

J. Am. Chem. Soc.

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The five-coordinate iron porphyrin carbene complexes [Fe(TPP) (CCl)] (TPP = tetraphenylporphyrin), [Fe(TTP) (CCl)] (TTP = tetratolylporphyrin) and [Fe(TFPP) (CPh)] (TFPP = tetra(pentafluorophenyl)porphyrin), utilizing two types of carbene ligands (CCl and CPh), have been investigated by single crystal X-ray, XANES (X-ray absorption near edge spectroscopy), Mössbauer, NMR and UV-vis spectroscopies. The XANES suggested the iron(II) oxidation state of the complexes. The multitemperature and high magnetic field Mössbauer experiments, which show very large quadrupole splittings (QS, ΔE), determined the S = 0 electronic configuration. More importantly, combined structural and Mössbauer studies, especially the comparison with the low spin iron(II) porphyrin complexes with strong diatomic ligands (CS, CO and CN) revealed the covalent bond nature of the carbene ligands. A correlation between the iron isomer shifts (IS, δ) and the axial bond distances is established for the first time for these donor carbon ligands (:C-R).

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“…Close examination of Table 3 would find, although both complexes shared the same structural features of sixcoordination with hindered ligands and ruffled core conformation, [Fe(TTP) ( ligand σ-donation and iron π-back-donation to the ligand. 72,73 Thus, the smaller δ of [Fe(TTP)(1,3-Me 2 Imd) 2 ] is consistent with the stronger NHC bonding to iron.…”

Section: ■ Discussionmentioning

confidence: 81%

“…It is seen that the δ of [Fe(TTP)(1,3-Me 2 Imd) 2 ] (0.18–0.26) are considerably smaller than those of [Fe(TMP)(2-MeHIm) 2 ] (0.35–0.43 mm/s). Earlier studies have suggested that the isomer shifts of the iron will decrease both with an increase in ligand σ-donation and iron π-back-donation to the ligand. , Thus, the smaller δ of [Fe(TTP)(1,3-Me 2 Imd) 2 ] is consistent with the stronger NHC bonding to iron. …”

Section: Discussionmentioning

confidence: 89%

Perspectives on Ligand Properties of N-Heterocyclic Carbenes in Iron Porphyrin Complexes

Wang

Liu

et al. 2021

Inorg. Chem.

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There has been considerable research interest in the ligand nature of N-heterocyclic carbenes (NHCs). In this work, two six-coordinate NHC iron porphyrin complexes [FeII(TTP)(1,3-Me2Imd)2] (TTP = tetratolylporphyrin, 1,3-Me2Imd = 1,3-dimethylimidazol-2-ylidene) and [FeIII(TDCPP)(1,3-Me2Imd)2]ClO4 (TDCPP = 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin) are reported. Single-crystal X-ray characterizations demonstrate that both complexes have strongly ruffled conformations and relatively perpendicular ligand orientations which are forced by the sterically bulky 1,3-Me2Imd NHC ligands. Multitemperature (4.2–300 K) and high magnetic field (0–9 T) Mössbauer and low-temperature (4.0 K) EPR spectroscopies definitely confirmed the low-spin states of [FeII(TTP)(1,3-Me2Imd)2] (S = 0) and [FeIII(TDCPP)(1,3-Me2Imd)2]ClO4 (S = 1/2). The similarity of 1,3-Me2Imd and imidazole, as well as the well-established correlations between the ligand nature and spectroscopic characteristics of [FeII,III(Porph)(L)2]0,+ (Porph: porphyrin; L: planar base ligand) species, allowed direct comparisons between the pair of ligands which revealed for the first time that NHC has a stronger π-acceptor ability than imidazoles, in addition to its very strong σ-donation.

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Effects of the ligands on the electrochemical oxidation of (benzylydeneacetone)Fe(CO)2L, with L=CO, phosphines and phosphites

Cited by 7 publications

References 15 publications

A Rationale for the Linear Correlation of Aryl Substituent Effects in Iron(0) Tricarbonyl Complexes Containing α,β-Unsaturated Enone (Chalcone) Ligands

A Rationale for the Linear Correlation of Aryl Substituent Effects in Iron(0) Tricarbonyl Complexes Containing α,β-Unsaturated Enone (Chalcone) Ligands

Electronic Configuration and Ligand Nature of Five-Coordinate Iron Porphyrin Carbene Complexes: An Experimental Study

Perspectives on Ligand Properties of N-Heterocyclic Carbenes in Iron Porphyrin Complexes

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