Synthesis of α,ω-bis(diphenylphosphino)alkane and α,ω-bis(diphenylphosphino)(poly)ether ligands and complexes of rhodium(I)

Thewissen, D. H. M. W.; Timmer, K.; Noltes, J. G.; Marsman, J.W.; Laine, Richard M.

doi:10.1016/s0020-1693(00)86576-7

Cited by 36 publications

(9 citation statements)

References 26 publications

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“…The ligands 4aa (R = Me, R‘ = H) and 4ba (R = o -anisyl, R‘ = H) react with [Rh(COD)(THF) 2 ] [BF 4 ] to give the complexes [Rh(COD)( 4aa )][BF 4 ] ( 6aa ) and [Rh(COD)( 4ba )][BF 4 ] ( 6ba ) in good yields. The complexes 6aa and 6ba are characterized by 31 P{ 1 H} NMR spectroscopy, with a doublet at 29.7 and 39.1 ppm, respectively, and J RhP coupling constants of 152 Hz, typical for [Rh(COD)(PR 3 ) 2 ] + or [Rh(COD)(P-N)] + compounds. , In the 1 H NMR spectra, the olefinic protons in the trans position to phosphorus are observed at 5.43 (2H) ppm for both complexes, while those in the trans position relative to nitrogen appear at much higher field, at 4.15 (1H) and 3.96 (1H) ppm for 6aa and 3.83 (2H) ppm for 6ba . The splitting of the latter type of olefinic protons observable in the case of 6aa is a consequence of the asymmetry of the phosphorus environment.…”

Section: Resultsmentioning

confidence: 99%

Study of the Bonding Properties of the New Ligands C₅H₃N(2-R‘)(6-CH₂PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

1997

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The bonding properties of the optically active chiral-at-P polydentate ligands C5H3N(2-R‘)(6-CH2PPhR) (R = Me, R‘ = H, Me; R = o-anisyl, R‘ = H, Me) and the achiral ligand C5H3N(2-Me)(6-CH2PPh2) toward (COD)Rh+ are reported. The results show that steric hindrance of the 2-position of the pyridyl ring induces a labile character of the Rh−N bond. Moreover, for R = o-anisyl and R‘ = Me, a dynamic competition for bonding between the N- and O-donating centers is observed. Comparison of the solid state structures of complexes [Rh(COD)(C5H4N(2-CH2PPhMe)][BF4] and [Rh(COD)(C5H3N(2-Me)(6-CH2PPh2)][BF4] shows a significant bond lengthening of the Rh−N bond in the latter complex, consistent with its fluxional behavior observed in solution.

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Section: Resultsmentioning

confidence: 99%

Study of the Bonding Properties of the New Ligands C₅H₃N(2-R‘)(6-CH₂PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

1997

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“…ESI-MS were recorded on Bruker MicrOTOF and Bruker MicroOTOF-Q instruments. 58 The starting materials {Ph 2 P(CH 2 ) 2 } 2 O (POP 0 ), 59 Scheme 7. Suggested Reaction Pathways for Aldehyde Hydroacylation and Alkene Hydroacylation Figure 6.…”

Section: Methodsmentioning

confidence: 99%

Controlling Selectivity in Intermolecular Alkene or Aldehyde Hydroacylation Reactions Catalyzed by {Rh(L₂)}⁺Fragments

et al. 2010

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Rhodium(III) dihydrido complexes [Rh(L 2 )(H) 2 (acetone)][BAr F4 ] (Ar F =C 6 H 3 (CF 3 ) 2 ) containing the potentially hemilabile ligands L 2 = 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene (Xantphos) and [Ph 2 P(CH 2 ) 2 ] 2 O (POP 0 ) have been prepared from their corresponding norbornadiene rhodium(I) precursors. In solution these complexes are fluxional by proposed acetone dissociation, which can be trapped out by addition of MeCN to form [Rh(L 2 )(H) 2 (NCMe)][BAr F 4 ], which have been crystallographically characterized. Addition of alkene (methyl acrylate) to these complexes results in reduction to a rhodium(I) species and when followed by addition of the aldehyde HCOCH 2 CH 2 SMe affords the new acyl hydrido complexes [Rh(L 2 )(COCH 2 CH 2 SMe)H][BAr F 4 ] in good yield. The solid-state and solution structures show a tight binding of the POP 0 and Xantphos ligands, having a trans-arrangement of the phosphines with the central ether linkage bound. This is similar to the previously reported complex [Rh(DPEphos)-(COCH 2 CH 2 SMe)H][BAr F 4 ] (DPEphos=[Ph 2 P(C 6 H 4 )] 2 O). Unlike the DPEphos complex, the Xantphos and POP 0 ligated complexes are not effective catalysts for the hydroacylation reaction between methyl acrylate and HCOCH 2 CH 2 SMe. This is traced to their inability to dissociate the central ether link in a hemilabile manner to reveal a vacant site necessary for alkene coordination. Consistent with this lack of availability of the vacant site, these complexes also are stable toward reductive decarbonylation. Complexes [Rh(Ph 2 P(CH 2 ) n PPh 2 )(acetone) 2 ][BAr F 4 ] (n = 2-5) have also been studied as catalysts for the hydroacylation reaction between methyl acrylate and HCOCH 2 CH 2 SMe at 22°C. As found previously, for n=2 this affords the product of alkene hydroacylation, but as the chain length is progressively increased to n=5, the reaction also progressively changes to favor the product of aldehyde hydroacylation. This is suggested to occur by a decrease in the accessibility of the metal site on increasing the bite angle of the chelate ligand, so that alkene coordination to a putative Rh(III)-acyl hydrido intermediate is progressively disfavored and aldehyde coordination (followed by hydride transfer) is progressively favored. These, and previous, results show that the overall conversion in the hydroacylation reaction can be controlled by the hemilabile nature of the chelating phosphine in the catalyst (e.g., DPEphos versus Xantphos), and the course of the reaction can also be tuned by changing the bite angle of the phosphine, cf. Ph 2 P(CH 2 ) 2 PPh 2 and Ph 2 P(CH 2 ) 5 PPh 2 .

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“…Mesitylene and methyl iodide were freshly distilled from sodium and anhydrous CaCl 2 , respectively. All chemicals were purchased from Acros Chimica or Aldrich Chemical Co. Bis(2-iodoethyl) ether, bis[2-(diphenylphosphino)ethyl] ether, Cl 2 PNEt 2 , and (4-bromobenzyl)diethylamine 24 were prepared according to literature procedures. For column chromatography, both silica gel 60 (Merck, 230−400 mesh) and aluminium oxide (activated neutral, 50−200 micron, Acros) were used.…”

Section: Methodsmentioning

confidence: 99%

“…Phosphino ethers are potentially both oxygen- and phosphorus-donor ligands. Complexes have been reported in which POP only functions as a cis-coordinated phosphorus bidentate ligand, such as in [(POP)NiCl 2 ], − [(POP)Rh(COD)][ClO 4 ], and [(POP)Pd(CH 3 CN) 2 ][BF 4 ] 2 [(POP)Pd(PEt 3 )][BF 4 ] 2 , [(POP)Rh(H) 2 (MeOH)][BF 4 ], and [(POP)Rh(CO)][PF 6 ] .…”

Section: Introductionmentioning

confidence: 99%

Novel Amphiphilic Diphosphines: Synthesis, X-ray Structure, Rhodium Complexes, Use in Hydroformylation, and Rhodium Recycling

Buhling¹,

Kamer²,

Leeuwen³

et al. 1997

Organometallics

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Three novel amphiphilic diphosphines have been synthesized: bis[2-(phenyl(3-pyridyl)-phosphino)ethyl] ether (POPpy) and bis [2-((4-((diethylamino), and 4,6-bis[bis(4-((diethylamino)methyl)phenyl)phosphino]-10,10-dimethylxanthene (xantham), based on 4,6-bis(diphenylphosphino)-10,10-dimethylxanthene (Xantphos). The crystal structure of xantham has been determined. Solution structures of rhodium xantham complexes have been studied using NMR and IR spectroscopy. When POPam is used in the hydroformylation of oct-1-ene, a linear/branched ratio (l/b) of 7.3 is achieved (88% nonanal) without isomerization to oct-2-ene. The use of POPpy results in an activity that is twice as high, a higher l/b-ratio of 9, and 0.7% isomerization. When xantham is used in the hydroformylation of hex-1-ene, oct-1-ene, and dodec-1-ene (80°C, 20 bar of syngas, toluene), l/b-ratios of 50 have been achieved (94% nonanal) together with 4% of isomerized octenes. The pHdependent distribution characteristics of the free ligands have been determined, and it is shown that POPpy, POPam, and xantham can be extracted for 40% from a Et 2 O solution into an aqueous solution of H 2 SO 4 at pH values of, respectively, 2.5, 5, and 5. Rhodium recycling experiments using POPam and xantham show that rhodium can be extracted into an aqueous layer at pH 5-5.5 for more than 99.95%, as determined by ICP-AES analysis, which allows complete separation of the product aldehydes and catalyst. After neutralization of the aqueous phase containing protonated POPam with an aqueous solution of NaHCO 3 , only 65% of the rhodium can be re-extracted into fresh toluene. In the case of xantham, 98% of the rhodium is re-extracted. Pressurizing the recovered rhodium and excess xantham to 20 bar at 80°C resulted in regeneration of the original active hydride complex, as judged by the retention of activity of up to 86%. POPpy has proved inappropriate for the recycling of rhodium.

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Synthesis of α,ω-bis(diphenylphosphino)alkane and α,ω-bis(diphenylphosphino)(poly)ether ligands and complexes of rhodium(I)

Cited by 36 publications

References 26 publications

Study of the Bonding Properties of the New Ligands C₅H₃N(2-R‘)(6-CH₂PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

Study of the Bonding Properties of the New Ligands C₅H₃N(2-R‘)(6-CH₂PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

Controlling Selectivity in Intermolecular Alkene or Aldehyde Hydroacylation Reactions Catalyzed by {Rh(L₂)}⁺Fragments

Novel Amphiphilic Diphosphines: Synthesis, X-ray Structure, Rhodium Complexes, Use in Hydroformylation, and Rhodium Recycling

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Synthesis of α,ω-bis(diphenylphosphino)alkane and α,ω-bis(diphenylphosphino)(poly)ether ligands and complexes of rhodium(I)

Cited by 36 publications

References 26 publications

Study of the Bonding Properties of the New Ligands C5H3N(2-R‘)(6-CH2PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

Study of the Bonding Properties of the New Ligands C5H3N(2-R‘)(6-CH2PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

Controlling Selectivity in Intermolecular Alkene or Aldehyde Hydroacylation Reactions Catalyzed by {Rh(L2)}+Fragments

Novel Amphiphilic Diphosphines: Synthesis, X-ray Structure, Rhodium Complexes, Use in Hydroformylation, and Rhodium Recycling

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Study of the Bonding Properties of the New Ligands C₅H₃N(2-R‘)(6-CH₂PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

Study of the Bonding Properties of the New Ligands C₅H₃N(2-R‘)(6-CH₂PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

Controlling Selectivity in Intermolecular Alkene or Aldehyde Hydroacylation Reactions Catalyzed by {Rh(L₂)}⁺Fragments