Platinum chelating phosphines

Chelating phosphines can be used to generate Ph2PCH2CH2CH2P(H)Ph, Cy2PCH2CH2CH2P(H)Ph P(H)Ph with platinum(II) halides in the presence complexes of type (149).1431,1432... 

The carbon diselenide and carbon sulfide selenide complexes of platinum(0) can be synthesized from Pt(PPh3)3. Reaction of the compounds with chelating phosphines results in substitution of the triphenylphosphines (equation 541).1866 With COS the C,S-bonded compound Pt(COS)(PPh3)2 is formed from Pt(PPh3)3. The reaction can also be used to prepare the dithiocarbonato complex Pt(S2CO)(PPh3)2.1867... 

High n/b ratios (3.7-13) are obtained in the platinum-catalyzed hydrofbrmylation reaction n/b ratios as high as 99 have been obtained utilizing a chelating phosphine, trans-1,2-diphenylphosphinocyclo-butane.10... 

Detailed NMR studies on several monoalkylpalladium and platinum complexes bearing nonsymmetrical chelating phosphine ligands revealed that the CO insertion occurs via alkyl migration as shown in Scheme 7.7 [45,46]. 

Although the oxidative addition of the C-H o-bond to the transition metal complex is difficult, the oxidative addition of methane derivative to a palla-dium(O) complex was experimentally proposed [19], where a chelate phosphine was employed as a ligand and two electron-withdrawing substituents were introduced to the sp C atom. The C-H o-bond activation of methane by palladium(O) and platinum(O) chelate phosphine complexes was theoretically investigated [8e, 20], as shown in Fig. 3. When monodentate phosphine was employed, the C-H bond is lengthened very much in the transition state and the geometry of the transition state is similar to that of the product. When the chelate phosphine was employed, the Pd-C, Pd-H, and C-H distances in the... 

In some similar chelating phosphine complexes, replacement of triflate by carbonyl proceeds with reduction of the platinum(ii) centee to a platinum(i) dimer. When the dppm complex 11 (//=1) is reacted with carbon monoxide, the phosphine ends up in a bridging form in the product 12, whereas when the dppe complex ll n = 2) s reacted, the... 

Bartik, T. Bunn, B.B. Bartik, B. Hanson, B.E. (1994) Synthesis, reactions, and catalytic chemistry of the water-soluble chelating phosphine l,2-bis[bis(m-sodiosulfonatophenyl)-phosphinojethane (dppets) complexes with nickel, palladium, platinum, and rhodium, Inorg. Chem., 33, 164-9. 

R SiH and CH2= CHR interact with both PtL and PtL 1. Complexing or chelating ligands such as phosphines and sulfur complexes are exceUent inhibitors, but often form such stable complexes that they act as poisons and prevent cute even at elevated temperatures. Unsaturated organic compounds are preferred, such as acetylenic alcohols, acetylene dicarboxylates, maleates, fumarates, eneynes, and azo compounds (178—189). An alternative concept has been the encapsulation of the platinum catalysts with either cyclodextrin or in thermoplastics or siUcones (190—192). 

The cyclometallated palladium and platinum derivatives of trimesityl phosphine or arsine react with pyrazole or 3,5-dimethylpyrazole to form metal chelates 243 (E = P, As M = Pd, Pt R = H, Me) having the trans configuration (81TMC24). 

Chelate complexes could only be prepared in the case of platinum(II) as the metal ion, while the group V atom alone acted as a donor toward palladium(II) and mercury(II). The coordinated olefin in the chelate complexes was found to be readily displaced by monodentate ligands such as tertiary arsines, -toluidine and the thiocyanate ion. It was suggested by these workers that chelation would take place more readily if the olefinic phosphine or arsine were subject to greater steric restrictions than was the pentenyl ligand. 

Kneen has also used the ligand ortho-2-methallylphenyl-diphenyl-phosphine, mp, to prepare the chelate complexes PtBr2 (mp) and PdCl2 (mp). The platinum complex reacted with bromine to give a red oil which was not investigated further. 

The ligand ap reacts with (norbornadiene) M (CO) 4 (M = Cr, Mo, W) (vide infra), to give complexes (phosphine) M (CO)4. The phosphine is not coordinated as ap but as ortho-cis-propenyl-phenyldiphenylphosphine (pp) the production of this species is discussed below. There is no evidence that this isomerisation takes place on coordination to platinum (II) or palladium(II). The chelate complex PtBr2 (pp) was prepared by Interrante (20) and shown by its spectral properties to be distinct from PtBr2 (ap). 

Nucleophihc attack of methoxide ion on olefinic and acetylenic groups of suitable unsaturated phosphine complexes of platinum(II) takes place to give cyclic, a-bonded complexes. This reaction appears to occur whether or not the unsaturated group is coordinated to the metal (22). But-3-enyl diphenylphosphine forms a chelate complex with platinum(II) chloride which on treatment with sodium hydrogen car-... 

Oriho-vinylbenzenethiol forms similar polymeric and hexameric complexes (55) which can be converted to monomers by reaction with two moles of triphenylphosphine per platinum. Attempts were made to remove one phosphine to give a chelate, using anhydrous silver perchlorate the product isolated had the unusual structure shown in Fig. 41. 

Aresta (54) and Deutscher (56) have also prepared chelate complexes by reacting the Giignard reagent formed from platinum bromide. The structure shown in Fig. 42 a has been attributed to the product of this reaction on the basis of its i.r. spectrum. Triphenyl phosphine displaces the coordinated double bonds to peld the complex... 

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