18583-19-2Relevant academic research and scientific papers
Isolation and characterization of the acyl complexes trans- (R=n-Bu or s-Bu) and their relevance to the hydroformylation of linear butenes catalyzed by platinum/tin/triphenylphosphine catalytic systems. Molecular structure of cis-
Cavinato, G.,Munno, G. De,Lami, M.,Marchionna, M.,Toniolo, L.,Viterbo, D.
, p. 277 - 282 (1994)
The acyl complex trans- (A) has been synthesized by reaction of with 1-butene under 100 atm of CO at 80-100 deg C, in ethanol.With 2-butene rather than 1-butene under the same conditions, a mixture of the above acyl complex and of trans- (B) was formed.Complexes A and B do not interconvert.The new acyl complexes A and B have been characterized by IR and 1H NMR and 13C NMR spectroscopy.The ratio A/B increases with PPh3/Pt ratio and with temperature.The formation of two isomers when 2-butene is used involves an isomerization process which is likely to be limited to the alkyl precursor complexes.The reactivity of complexes A and B has been tested in reactions with SnCl2, H2, HCl and trans-.From the reaction solutions crystals of cis- have been obtained.Its molecular structure has been determined by X-ray diffraction.The Pt atom has cis square planar coordination, with angular distortions due to steric factors.The strong trans influence of the SnCl3 group is confirmed by the lengthening of the trans Pt-P distance.The SnCl3 group has the pyramidal geometry found in all related compounds. Key words: Acyl; Butenes; Hydroformylation; Platinum; Tin
Stoichiometric model reactions in olefin hydroformylation by platinum-tin systems
Gómez, Montserrat,Muller, Guillermo,Sainz, Daniel,Sales, Joaquim,Solans, Xavier
, p. 4036 - 4045 (2008/10/08)
The three independent steps involved in the hydroformylation process, insertion of the olefin, insertion of carbon monoxide, and hydrogenolysis, have been investigated with use of platinum-tin catalysts and 1-pentene as olefin at low pressure and temperature in CH2Cl2. In the temperature range 198-308 K, the three reactions can be studied consecutively. All the intermediates observed were prepared and characterized separately. The complex trans-[PtH(SnCl3) (PPh3)2] was used as the initial compound for this sequence. The hydrido complex crystallized in the monoclinic space group C2/c, with a = 31.345 (5) ?, b = 12.716 (3) ?, c = 18.135 (3) ?, β = 96.5 (2)°, Z = 8, and R (Rw) = 0.056 (0.060) for 3235 independent reflections having I > 2.56σ(I). The large Pt-Sn bond (2.601 (1) ?) distance correlates satisfactorily with the low 1J(Pt-Sn) value. The Pt-Sn bond is necessary for the insertion of 1-pentene in the hydrido-platinum complex and for the hydrogenolysis of the acyl compounds under these mild conditions. The insertion of 1-pentene was observed at 198 K, giving the cis-alkyl complex; CO insertion took place after isomerization to the trans-alkyl complex. The instability of Pt-Sn and Pt-C bonds in the trans-acyl complex favors easy decarbonylation or loss of SnCl2, so any other platinum complex without tin accepts SnCl2 from the acyl complex. The hydrogenolysis of trans-[Pt(SnCl3) (COC5H11) (PPh3)2] under 1.5 bar of H2-CO (1:1) did not yield n-hexanal quantitatively; only 12% of n-hexanal was formed. Thus, decarbonylation was the main process observed. From the reactions studied, it is possible to propose the following order of Pt-Sn bond stability: trans-[Pt(SnCl3)(COC5H11)(PPh3) 2] 3)(C5H11)(PPh3)2] 3)(PPh3)2] 3)(CO)(PPh3)2] 3)(PPh3)]2 3)(PPh3)]- 2(SnCl3)2]2-. The insertion reactions studied with cis-[PtCl2(olefin)(PR3)] as an olefin carrier and the hydrido-platinum complexes trans-[PtHCl(PPh3)2], trans-[PtH(SnCl3)(PPh3)2], and [PtH(SnCl3)-(CO)(PPh3)2] as hydrogen carriers exclude the participation of intermolecular steps by reaction of two different platinum complexes under the experimental conditions described.
Role of the trichlorostannyl ligand in homogeneous catalysis. 3. Solvent effects on the reactions of cis-[PtCl2(L)(PR3)] and [Pt2(μ-Cl)2Cl2(PR3)2] (L = CO, SMe2; R = Ph, Et) with SnCl2·2H2O
Anderson, Gordon K.,Clark, Howard C.,Davies, Julian A.
, p. 434 - 438 (2008/10/08)
The reactivity of cis-[PtCl2(CO)(PPh3)] toward SnCl2·2H2O has been studied with use of acetone, acetonitrile, and chloroform as solvents. In acetone and acetonitrile, ligand rearrangement reactions occur, but in chloroform only the simple insertion of SnCl2 into one Pt-Cl bond is observed. Similar solvent effects are observed in the reactions of [Pt2(μ-Cl)2Cl2(PR3)2] with SnCl2·2H2O, which yield the trans-[PtCl(SnCl3)2(PR3)]- anions in acetone solution but the simple insertion products, [Pt2(μ-Cl)2(SnCl3)2(PR 3)2], in chloroform solution. Reactions of the related complexes cis-[PtCl2(L)(PPh3)] (L = SMe2, C5H5N, p-MeC6H4NH2) with SnCl2·2H2O in acetone solution also occur via ligand rearrangements. 1H, 31P{1H}, and 119Sn{1H} NMR methods, utilizing 13C-labeled carbon monoxide as a probe of geometry, have been employed to assign solution structures and to monitor reaction pathways.
