A New Highly Active Diphosphane-Palladium(II) Complex as a Catalyst Precursor for the Heck Reaction

Sjövall, Sven; Johansson, Maria H.; Andersson, Carina

doi:10.1002/1099-0682(200111)2001:11<2907::aid-ejic2907>3.0.co;2-7

Cited by 24 publications

(8 citation statements)

References 10 publications

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“…The solid state structure of 2b has been established unequivocally by X-ray diffraction studies (vide infra), whereas the bimolecular structure proposed for 2c is tentative and based on a correct elemental analysis for {(i-Pr 2 POCH 2 ) 2 CH 2 }NiCl 2 } n and by analogy to previously reported formation of such macrocyclic bimetallic products from the reaction of Pd and Pt halides with analogous pincer-type PCP ligands. 7b, 10,16,17 Reactions of (pz*CH 2 ) 2 CH 2 , 3…”

Section: Resultsmentioning

confidence: 99%

Ni(ii) complexes featuring non-metallated pincer-type ligands

2008

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Attempts to prepare pincer-type Ni complexes from the ligands (i-Pr(2)POCH(2))(2)CH(2) and (pz*CH(2))(2)CH(2) (pz* = 3,5-dimethylpyrazol-1-yl) gave instead the complexes cis-{kappa(P),kappa(P')-(i-Pr(2)POCH(2))(2)CH(2)}NiCl(2) and {kappa(N),kappa(N')-(pz*CH(2))(2)CH(2)}NiBr(2). X-Ray diffraction studies confirmed that these potentially pincer-type ligands have not undergone metallation, serving instead as chelating ligands in essentially square-planar or tetrahedral complexes. Heating of these compounds failed to induce metallation of the coordinated ligands.

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Section: Resultsmentioning

confidence: 99%

Ni(ii) complexes featuring non-metallated pincer-type ligands

2008

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“…In previous syntheses of ligand 1 the purification and identification of the product was hampered by the oxygen sensitivity of this diphosphine and hence it has been converted to the corresponding phosphine sulfide, which was isolated and fully characterised. 4a Previous attempts to cleanly remove the sulfur on the PCP ligand with Raney-nickel or trichlorosilane have been unsuccessful 16 and we decided to use LiAlH 4 in THF. The reaction of 4 with LiAlH 4 in THF at 150 • C over 3 d gave 1 as a single product with H 2 S as a by-product, cf.…”

Section: Reduction Of 13-cis-bis[(di-tert-butylthiophosphoryl)methyl]...mentioning

confidence: 99%

Synthesis and characterisation of PCsp3P phosphine and phosphinite platinum(ii) complexes. Cyclometallation and simple coordination

2007

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New and improved preparative routes to the previously known PCP ligands cis-1,3-bis(di-isopropylphosphinito)cyclohexane and cis-1,3-bis[(di-tert-butylphosphino)methyl]cyclohexane are reported. They react with 1 equivalent of dichloro(1,5-cyclooctadiene)platinum(II) [(COD)PtCl2] to give the cis coordinated complex cis-[PtCl2{cis-1,3-bis(di-isopropylphosphinito)}cyclohexane] and the C(sp3)-H activated complex trans-[PtCl{cis-1,3-bis(di-tert-butylphosphino)}cyclohexane]. The new PCP ligand cis-1,3-bis(di-tert-butylphosphinito)cyclohexane was synthesised and reacts with [(COD)PtCl2] giving the di-nuclear trans-[PtCl2{cis-1,3-bis(di-tert-butylphosphinito)cyclohexane}]2, which is highly insoluble. All metal complexes were characterised with X-ray crystallography. DFT calculations indicate that the inability of the phosphinite ligands to cyclometallate is due to a kinetic barrier, possibly involving an axial-equatorial conformational change necessary for the C-H activation process.

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“…enabled by the diaxial orientation of the cyclohexane substituents. 12 Interestingly, this connection between C-H activation ability and phosphorus atom substituents is not found for the fully analogous aromatic phosphines, which are known to cyclometallate readily with transition-metal centres. 13 The weakly coordinated trifluoracetato ligand in 4 is easily substituted and anion metathesis employing an excess of NaI in THF afforded complex 5 cleanly (Scheme 2).…”

Section: Complexationmentioning

confidence: 99%