Ligand effects and nucleophilic addition to (.eta.3-allyl)palladium complexes. A carbon-13 NMR study

Aakermark, Bjoern; Krakenberger, Bertil; Hansson, Susanne; Vitagliano, Aldo

doi:10.1021/om00146a031

Cited by 168 publications

(107 citation statements)

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“…25 ppm), testifying the higher trans-influence of the carbene with respect to sulfur or nitrogen donor atoms [20]. Finally, the IR spectra of the complexes display the typical strong peaks of the perchlorate at ca.…”

Section: Characterization Of Palladium(ii) Allyl Complexes Bearing Bimentioning

confidence: 86%

Synthesis, characterization and a reactivity study of some allyl palladium complexes bearing bidentate hemi-labile carbene or mixed carbene/PPh3 ligands

et al. 2016

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a b s t r a c tWith the aim at synthesizing novel allyl complexes that can potentially act as catalysts in the Tsuji-Trost catalyzed reaction, we have synthesized and characterized some allyl and 2-Meallyl palladium derivatives with one hemilabile bidentate or two strong mono-coordinating spectator ligands. The hemilabile ligands are constituted by one nitrogen heterocyclic carbene (NHC) fragment acting as the pivot bearing a labile wing with a pyridine nitrogen or sulfur atom as the second stabilizing atom. One of two monodentate ligands is in all cases PPh 3 whereas the other is a mono-or partially coordinated hemilabile carbene. The complexes were characterized by standard spectroscopic methods and elemental analysis and in two cases by SC-XRD technique.The reactivity of two selected complexes toward the Tsuji-Trost reaction was tested by stoichiometric allyl amination carried out with piperidine and the results of such a mechanistic investigation integrated by a computational study are also reported in this paper.

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Section: Characterization Of Palladium(ii) Allyl Complexes Bearing Bimentioning

confidence: 86%

Synthesis, characterization and a reactivity study of some allyl palladium complexes bearing bidentate hemi-labile carbene or mixed carbene/PPh3 ligands

et al. 2016

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“…[36] The preferential nucleophilic attack at one specific allyl carbon atom is another way to achieve high enantioselectiv- Table 1. 13 C NMR spectroscopic data for allylic carbon atoms in complexes 1 and 2 [14,23,28,37] For complexes 1 and 2, ∆δ lies between 35.7 and 27.2 ppm depending on the isomer (see Table 1). Such a high ∆δ is usual for N,P ligands, given the very different trans influence of the phosphorus and nitrogen atoms, [26] and reveals a higher electrophilicity for the C-1 atom (trans-P) than for the C-3 atom (cis-P; see Scheme 2). This feature has also been observed in the solid state, since the PdϪC distances are longer for C transP than those for C cisP .…”

Section: Nmr Spectroscopic Studies On Allylic Compounds 1 Andmentioning

confidence: 88%

“…[26,42] For the 1-butenyl complexes, the coupling constants involving the external methyl moiety, 4 J H,P and 3 J C,P , enable the establishment of the cis-P/trans-P ratio, whereas δ 1 H is not diagnostic of the relative orientation. Indeed, for 1-butenyl (R ϭ Me) complexes based on other types of N,P ligands, van Leeuwen has proposed that the signal for the methyl group should be found at δ Ͼ 1.3 ppm when in the trans-P position and at δ Ͻ 0.6 ppm when in the cis-P position.…”

mentioning

confidence: 99%

Allylpalladium(II) Complexes with Aminophosphane Ligands: Solution Behaviour and X‐ray Structure of cis‐[Pd(η³‐CH₂CHCHPh){Ph₂PCH₂CHPhNH(2,6‐C₆H₃iPr₂)}][PF₆]

et al. 2004

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A new β-aminophosphane L 2 [Ph 2 PCH 2 CH(Ph)NH(2,6-C 6 H 3 iPr 2 )], bearing an asymmetric carbon atom and a vicinal prochiral nitrogen centre and (η 3 -allyl)palladium complexes of general formula [Pd(η 3 -C 3 H 4 R){η 2 -Ph 2 PCH 2 CH-(Ph)NHAr}][PF 6 ] (1−6) (R = H, Me or Ph and Ar = Ph or 2,6-C 6 H 3 iPr 2 ) have been synthesised. NMR spectroscopic studies and a crystal structure analysis of complex 6 (R = Ph, Ar = 2,6-C 6 H 3 iPr 2 ) confirmed the highly diastereoselective coordination of the nitrogen atom. Because of the allyl fluxionality and the presence of asymmetric centres, all the complexes exist in solution as mixtures of up to four diastereomers. For the monosubstituted allyl complexes [Pd(η 3 -C 3 H 4 R){Ph 2 PCH 2 CH(Ph)NHAr}][PF 6 ] (3−6, R = Me or Ph) only cis/trans-P and endo/exo isomers with syn-oriented allyl substituents have been observed in solution. The diastereom-

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“…Such a situation is the most usual and experimentally verified and gives rise to a distribution of the species governed by the mutual equilibrium constants. In order to rationalize these observations let us first suppose that the addition of equimolecular amounts of the ligands A and B to a generic species ML 2 …”

Section: Formation Of the Mixed Complexesmentioning

confidence: 99%

“…The synthesis of the allyl derivatives bearing phosphanes and isocyanides ([Pd(g 3 -allyl)(L 0 )(L 00 )]ClO 4 ), was indeed trivial since the complexes required were obtained by simple addition of equimolecular amounts of phosphane and isocyanide to a CH 2 Cl 2 solution of the allyl dimer [Pd (g 3 -allyl)(l-Cl)] 2 dechlorinated with NaClO 4 [1,2]. We have also noticed that a non statistical mixture of homoleptic and mixed complexes was obtained when equimolecular solutions of different ligands (L 0 = phosphites, L 00 = isocyanides, and phosphanes) were added to the dechlorinated allyl dimer obtained as previously described.…”

Section: Introductionmentioning

confidence: 99%

Facile synthesis and reactivity study of mixed phosphane–isocyanide Pd(II) and Pd(0) complexes

Canovese

Visentin

Levi

et al. 2011

Inorganica Chimica Acta

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a b s t r a c tThe reaction between an equimolecular mixture of isocyanide CNR (CNR = di-methylphenyl isocyanide (DIC), tert-butyl isocyanide (TIC), triphenyl phosphane (PPh 3 ) and a dechlorinated solution of the palladium allyl dimers [Pd(g 3 -allyl)Cl] 2 (allyl = 2-Meallyl, 1,1-Me 2 allyl) in stoichiometric ratio yields the mixed derivative [Pd(g 3 -allyl)(CNR)(PPh 3 )] only. Apparently, the mixed derivative represents the most stable species among all the possible ones that might be formed under those experimental conditions. Theoretical calculations are in agreement with the experimental observation and the energy stabilization of the mixed species with respect to the homoleptic derivatives is traced back to an overall push-pull effect exerted by the isocyanide and the phosphane acting synergically. Similar behavior is observed in the case of the synthesis of the palladacyclopentadienyl complexes [Pd(C 4 (COOMe) 4 )(CNR)(PPh 3 )] and of the palladium(0) olefin complexes whose synthesis invariably yields the mixed [Pd(g 2 -olefin)(CNR)(PPh 3 )] derivatives. The paper includes studies on the reactivity toward allylamination in the case of the palladium(II) allyl complexes. A diffractometric investigation on the solid state structures of four different palladium isocyanide-phosphane complexes is also included.

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Ligand effects and nucleophilic addition to (.eta.3-allyl)palladium complexes. A carbon-13 NMR study

Cited by 168 publications

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Synthesis, characterization and a reactivity study of some allyl palladium complexes bearing bidentate hemi-labile carbene or mixed carbene/PPh3 ligands

Synthesis, characterization and a reactivity study of some allyl palladium complexes bearing bidentate hemi-labile carbene or mixed carbene/PPh3 ligands

Allylpalladium(II) Complexes with Aminophosphane Ligands: Solution Behaviour and X‐ray Structure of cis‐[Pd(η³‐CH₂CHCHPh){Ph₂PCH₂CHPhNH(2,6‐C₆H₃iPr₂)}][PF₆]

Facile synthesis and reactivity study of mixed phosphane–isocyanide Pd(II) and Pd(0) complexes

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Ligand effects and nucleophilic addition to (.eta.3-allyl)palladium complexes. A carbon-13 NMR study

Cited by 168 publications

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Synthesis, characterization and a reactivity study of some allyl palladium complexes bearing bidentate hemi-labile carbene or mixed carbene/PPh3 ligands

Synthesis, characterization and a reactivity study of some allyl palladium complexes bearing bidentate hemi-labile carbene or mixed carbene/PPh3 ligands

Allylpalladium(II) Complexes with Aminophosphane Ligands: Solution Behaviour and X‐ray Structure of cis‐[Pd(η3‐CH2CHCHPh){Ph2PCH2CHPhNH(2,6‐C6H3iPr2)}][PF6]

Facile synthesis and reactivity study of mixed phosphane–isocyanide Pd(II) and Pd(0) complexes

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Allylpalladium(II) Complexes with Aminophosphane Ligands: Solution Behaviour and X‐ray Structure of cis‐[Pd(η³‐CH₂CHCHPh){Ph₂PCH₂CHPhNH(2,6‐C₆H₃iPr₂)}][PF₆]