- Topotactic Synthesis of Phosphabenzene-Functionalized Porous Organic Polymers: Efficient Ligands in CO2 Conversion
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Progress toward the preparation of porous organic polymers (POPs) with task-specific functionalities has been exceedingly slow—especially where polymers containing low-oxidation phosphorus in the structure are concerned. A two-step topotactic pathway for the preparation of phosphabenzene-based POPs (Phos-POPs) under metal-free conditions is reported, without the use of unstable phosphorus-based monomers. The synthetic route allows additional functionalities to be introduced into the porous polymer framework with ease. As an example, partially fluorinated Phos-POPs (F-Phos-POPs) were obtained with a surface area of up to 591 m2 g?1. After coordination with Ru species, a Ru/F-Phos-POPs catalyst exhibited high catalytic efficiency in the formylation of amines (turnover frequency up to 204 h?1) using a CO2/H2 mixture, in comparison with the non-fluorinated analogue (43 h?1) and a Au/TiO2 heterogeneous catalysts reported previously (?1). This work describes a practical method for synthesis of porous organic phosphorus-based polymers with applications in transition-metal-based heterogeneous catalysis.
- Yang, Zhenzhen,Chen, Hao,Li, Bo,Guo, Wei,Jie, Kecheng,Sun, Yifan,Jiang, De-en,Popovs, Ilja,Dai, Sheng
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- 2,4,6-Triphenylphosphinine and 2,4,6-triphenylposphabarrelene revisited: Synthesis, reactivity and coordination chemistry
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The synthesis of 2,4,6-triphenylphosphinine has been revisited and a general protocol for the preparation of such low-coordinate phosphorus compounds in good to excellent yields could be established. This allows to investigate several aspects of the chemistry of 2,4,6-triarylphosphinine, such as the reaction with in situ generated benzyne to give 2,4,6-triphenylphosphabarrelene. The corresponding 2,4,6-triphenylphosphabarrelene-selenide could be characterized crystallographically for the first time and the structural and electronic properties of this cage-compound in comparison to classical triarylphosphines could be evaluated. Moreover, [(L)W(CO)5)] complexes of both 2,4,6-triphenylphosphinine and 2,4,6-triphenylphosphabarrelene were prepared and characterized by means of X-ray crystallography. This allowed for the first time a direct structural comparison of these related phosphorus compounds, coordinated to the same metal fragment.
- Rigo,Sklorz,Hatje,Noack,Weber,Wiecko,Müller
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supporting information
p. 2218 - 2226
(2016/02/09)
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- Cyclometalation of aryl-substituted phosphinines through C-H-bond activation: A mechanistic investigation
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A series of 2,4,6-triarylphosphinines were prepared and investigated in the base-assisted cyclometalation reaction using [Cp*IrCl2] 2 (Cp=1,2,3,4,5-pentamethylcyclopentadienyl) as the metal precursor. Insight in the mechanism of the C-H bond activation of phosphinines as well as in the regioselectivity of the reaction was obtained by time-dependent 31P{1H}NMR spectroscopy. At room temperature, 2,4,6-triarylphosphinines instantaneously open the Ir-dimer and coordinate in an η1-fashion to the metal center. Upon heating, a dissociation step towards free ligand and an Ir-acetate species is observed and proven to be a first-order reaction with an activation energy of ΔE A=56.6kJ mol-1 found for 2,4,6-triphenylphosphinine. Electron-donating substituents on the ortho-phenyl groups of the phosphorus heterocycle facilitate the subsequent cyclometalation reaction, indicating an electrophilic C-H activation mechanism. The cyclometalation reaction turned out to be very sensitive to steric effects as even small substituents can have a large effect on the regioselectivity of the reaction. The cyclometalated products were characterized by means of NMR spectroscopy and in several cases by single-crystal X-ray diffraction. Based on the observed trends during the mechanistic investigation, a concerted base-assisted metalation-deprotonation (CMD) mechanism, which is electrophilic in nature, is proposed. Finely tuned: A series of substituted 2,4,6-triarylphosphinines were prepared and investigated in a base-assisted cyclometalation reaction using [Cp*IrCl 2]2 (Cp=1,2,3,4,5-pentamethylcyclopentadienyl) as the metal precursor M (see figure). Insight into the mechanism of the C-H bond activation of phosphinines as well as into the regioselectivity of the reaction was obtained by using time-dependent 31P{1H}NMR spectroscopy and single-crystal X-ray diffraction. Copyright
- Broeckx, Leen E. E.,Güven, Sabriye,Heutz, Frank J. L.,Lutz, Martin,Vogt, Dieter,Müller, Christian
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supporting information
p. 13087 - 13098
(2013/10/01)
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- Novel cofacial oxidative coupling reaction of phosphinine in the presence of Cu(I) and ClO4-
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2,4,6-Triphenylphosphinine (TPP) underwent unprecedented cofacial oxidative coupling to form a novel C2-symmetric cage compound, having extremely long C-C bonds.
- Kojima, Takahiko,Ishioka, Yoshitaka,Matsuda, Yoshihisa
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p. 366 - 367
(2007/10/03)
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- Phosphabenzenes as electron withdrawing phosphine ligands in catalysis
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The utility of phosphabenzenes as ligands in late transition metal catalysis is examined. Molecular orbital calculations indicate that phosphabenzenes possess a low lying LUMO permitting π-back bonding interactions. The resultant electron withdrawing natu
- DiMauro, Erin F.,Kozlowski, Marisa C.
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p. 439 - 444
(2007/10/03)
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- Phosphabenzenes as monodentate π-acceptor ligands for rhodium-catalyzed hydroformylation
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A new class of phosphinine/rhodium catalysts for the hydroformylation of terminal and internal alkenes is presented in this study. A series of phosphabenzenes 1-14 has been prepared by condensation of phosphane or tris(trimethylsilyl)phosphane with the corresponding pyrylium salt. Trans[(phosphabenzene)2RhCl(CO)] complexes 21-25 have been prepared and studied spectroscopically and by X-ray crystal-structure analysis, The hydroformylation of oct-1-ene has been used to identify optimal catalyst preformation and reaction conditions. Hydroformylation studies with 15 monophosphabenzenes have been performed. The catalytic performance is dominated by steric influences, with the phosphabenzene 8/rhodium system being the most active catalyst. Turnover frequencies of up to 45370 h-1 for the hydroformylation of oct-1-ene have been determined. In further studies, hydroformylation activity toward more highly substituted alkenes was investigated and compared with the standard industrial triphenylphosphane/rhodium catalyst. The reactivity differences between the phosphabenzene and the triphenylphosphane catalyst increase on going to the more highly substituted alkenes. Even tetra substituted alkenes reacted with the phosphabenzene catalyst, whereas the triphenylphosphane system failed to give any product. In situ pressure NMR experiments have been performed to identify the resting state of the catalyst. A monophosphabenzene complex [(phosphinine 8)Ir(CO)3H] could be detected as the predominant catalyst resting state.
- Breit, Bernhard,Winde, Roland,Mackewitz, Thomas,Paciello, Rocco,Harms, Klaus
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p. 3106 - 3121
(2007/10/03)
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- λ3-Phosphinines with a Functional Group at C-4
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Hitherto unknown derivatives of λ3-phosphinines with a functional substituent at C-4, such as CN (10), CO2CH3 (11), or CH2CN (5), as well as 4,4'-methylenebis(2,6-diphenyl)-λ3-phosphinine) (6) are prepared under mild conditions by reductive elimination of both methoxyl groups from the phosphorus atom of the 4-substituted 1,1-dimethoxy-2,6-diphenyl-λ5-phosphinines (2, 7).The new λ3-phosphinines are crystalline and except for 6 air-stable compounds, whose analytical and spectroscopic data are reported in the Tables 1 and 2.
- Dimroth, Karl,Kaletsch, Hans
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p. 1245 - 1248
(2007/10/02)
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- Phosphabenzene-Nickel Complexes
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The reaction of (COD)2Ni (1) or (COT)2Ni2 (11) with the 2,4,6-trisubstituted phosphabenzene derivatives 2 or 3 results in displacement of one COD or COT molecule to give the cycloolefinbis(phosphabenzene)-nickel complexes 6, 7 or 12, respectively.CDTNi (8
- Lehmkuhl, Herbert,Paul, Rainer,Mynott, Richard
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p. 1139 - 1146
(2007/10/02)
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