Activation and η<sup>2</sup>-co-ordination of arenes: crystal and molecular structure of an (η<sup>2</sup>-hexafluorobenzene)rhodium complex

Belt, Simon T.; Duckett, Simon B.; Helliwell, M.; Perutz, Robin N.

doi:10.1039/c39890000928

Cited by 62 publications

(53 citation statements)

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“…The 31 P{ 1 H} NMR spectrum shows a resonance at δ 3.09, as a doublet of doublets of doublets ( J RhP = 192, J PF = 56, 52 Hz). The value of J RhP indicates a Rh(I) oxidation state, 16 and the large values of J PF are similar to those for Rh(η 2 -C 6 F 6 ) complexes. 16 We therefore assign complex 2 as CpRh(PMe 3 )(η 2 -C 4 F 5 N) with the pentafluoropyridine bonded in an η 2 - C , C mode.…”

Section: Resultssupporting

confidence: 60%

“… 15 It reacts with benzene to yield CpRh(PMe 3 )(C 6 H 5 )H via a short-lived η 2 -arene complex. Photolysis with C 6 F 6 results in the isolation of the stable η 2 -hexafluorobenzene complex CpRh(PMe 3 )(C 6 F 6 ), 16 and reaction in pentafluoroanisole generates the metallacycle CpRh(PMe 3 )(κ 2 - C , C - C H 2 OC 6 F 4 ), characterized by multinuclear NMR spectroscopy; reaction of this complex with 1 equiv of [Ph 3 C] + [PF 6 ] − at 220 K generates [Cp(PMe 3 )Rh=C(H)OC 6 F 4 ]PF 6 . 17 …”

Section: Introductionmentioning

confidence: 99%

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Photochemical Reactions of Fluorinated Pyridines at Half-Sandwich Rhodium Complexes: Competing Pathways of Reaction

et al. 2013

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Irradiation of CpRh(PMe3)(C2H4) (1; Cp = η5-C5H5) in the presence of pentafluoropyridine in hexane solution at low temperature yields an isolable η2-C,C-coordinated pentafluoropyridine complex, CpRh(PMe3)(η2-C,C-C5NF4) (2). The molecular structure of 2 was determined by single-crystal X-ray diffraction, showing coordination by C3–C4, unlike previous structures of pentafluoropyridine complexes that show N-coordination. Corresponding experiments with 2,3,5,6-tetrafluoropyridine yield the C–H oxidative addition product CpRh(PMe3)(C5NF4)H (3). In contrast, UV irradiation of 1 in hexane, in the presence of 4-substituted tetrafluoropyridines C5NF4X, where X = NMe2, OMe, results in elimination of C2H4 and HF to form the metallacycles CpRh(PMe3)(κ2-C,C-CH2N(CH3)C5NF3) (4) and CpRh(PMe3)(κ2-C,C-CH2OC5NF3) (5), respectively. The X-ray structure of 4 shows a planar RhCCNC-five-membered ring. Complexes 2–5 may also be formed by thermal reaction of CpRh(PMe3)(Ph)H with the respective pyridines at 50 °C.

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Section: Resultssupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Photochemical Reactions of Fluorinated Pyridines at Half-Sandwich Rhodium Complexes: Competing Pathways of Reaction

et al. 2013

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“…One of the first investigations of C–F bond activation reactions at rhodium were probably triggered by studies on C–H bond activation in aromatic compounds. In 1989, Perutz and co‐workers reported their results on the photolytic activation of benzene at a {(Cp)Rh(PMe 3 )} moiety 24. They postulated an η 2 ‐precoordination of benzene prior to the oxidative addition step of a C–H bond to give [(Cp)Rh(H)(C 6 H 5 )(PMe 3 )] ( 4 ).…”

Section: C–f Bond Cleavage Reactionsmentioning

confidence: 99%

C–F Bond Activation of Highly Fluorinated Molecules at Rhodium: From Model Reactions to Catalysis

2011

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Rhodium complexes are excellent tools for the activation of aromatic and olefinic carbon–fluorine bonds. C–F bond cleavage reactions are key steps for the derivatization of highly fluorinated compounds via stoichiometric or catalytic reaction pathways. The reaction routes involve hydrodefluorinations, but also the selective introduction of functional groups at distinctive positions, to provide access to new fluorinated building blocks. One can identify two general types of rhodium precursors that can induce the C–F activation step. Cyclopentadienyl compounds have been applied for thermal and photochemical C–F bond cleavage reactions of aromatics in solution, but oxidative addition steps have also been investigated in matrix isolation studies at low temperature. Square‐planar hydrido, silyl, and boryl complexes are often involved in unique stoichiometric and catalytic processes for the derivatization of aromatics and olefins.

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“…Calculated binding energies (kJ•mol -1 ) of the {ReCp(CO) 2 } fragment to various arenes.With the exception of π-acidic HFB, which typically distorts away from planarity on binding,57,60,61 welldefined examples of partially coordinated fluorobenzenes are rare 62,64 Bimetallic 6 and 7 that feature bridging arenes are notable examples (Chart 4).65 The solid-state structure of 6 indicates μ-η 4 :η 4coordination of the FB, which is distorted dramatically away from planarity.…”

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Organometallic chemistry using partially fluorinated benzenes

2017

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Fluorobenzenes, in particular fluorobenzene (FB) and 1,2-difluorobenzene (1,2-DiFB), are increasingly becoming recognised as versatile solvents for conducting organometallic chemistry and transition-metal-based catalysis. The presence of fluorine substituents reduces the ability to donate π-electron density from the arene and consequently fluorobenzenes generally bind weakly to metal centres, allowing them to be used as essentially non-coordinating solvents or as readily displaced ligands. In this context, examples of well-defined complexes of fluorobenzenes are discussed, including trends in binding strength with increasing fluorination and different substitution patterns. Compared to more highly fluorinated benzenes, FB and 1,2-DiFB typically demonstrate greater chemical inertness, however, C-H and C-F bond activation reactions can be induced using appropriately reactive transition metal complexes. Such reactions are surveyed, including catalytic examples, not only to provide perspective for the use of FB and 1,2-DiFB as innocent solvent media, but also to highlight opportunities for their exploitation in contemporary organic synthesis.

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Activation and η²-co-ordination of arenes: crystal and molecular structure of an (η²-hexafluorobenzene)rhodium complex

Cited by 62 publications

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Photochemical Reactions of Fluorinated Pyridines at Half-Sandwich Rhodium Complexes: Competing Pathways of Reaction

Photochemical Reactions of Fluorinated Pyridines at Half-Sandwich Rhodium Complexes: Competing Pathways of Reaction

C–F Bond Activation of Highly Fluorinated Molecules at Rhodium: From Model Reactions to Catalysis

Organometallic chemistry using partially fluorinated benzenes

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Activation and η2-co-ordination of arenes: crystal and molecular structure of an (η2-hexafluorobenzene)rhodium complex

Cited by 62 publications

References 0 publications

Photochemical Reactions of Fluorinated Pyridines at Half-Sandwich Rhodium Complexes: Competing Pathways of Reaction

Photochemical Reactions of Fluorinated Pyridines at Half-Sandwich Rhodium Complexes: Competing Pathways of Reaction

C–F Bond Activation of Highly Fluorinated Molecules at Rhodium: From Model Reactions to Catalysis

Organometallic chemistry using partially fluorinated benzenes

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Activation and η²-co-ordination of arenes: crystal and molecular structure of an (η²-hexafluorobenzene)rhodium complex