Palladium and Platinum Units Grafted on the Periphery of Carbosilane Dendrimers

Abstract

The reaction of a series of phosphanyl-terminated carbosilane dendrimers with palladium and platinum complexes was carried out. The new metallodendrimers containing PdCl(η 3 -2-MeC 3 H 4 ) and PtCl 2 or Pt(CϵCPh) 2 as peripheral groups were characterized by 1 H, 13 C, 29 Si, 31 P, and 195 Pt NMR spectroscopy, and, in some cases, by mass spectrometry. The PtCl 2 -containing species of the second-generation carbosilane dendrimer displays only one of the two possible stereoisomers. By comparison with the 31 P NMR spectra of the model compounds cis-[PtCl 2 (PPh 2 CH 2 SiMe 3 ) 2 ] (4) and cis-

Dendrimers Containing Two Metallic Layers. Chloride Migration from Peripheral Gold, Palladium, or Rhodium Metals to Internal Ruthenium Atoms

“…Dendrimer 3 was used as starting material. The reaction of 3 with [PdCl(η 3 -2-MeC 3 H 4 )] 2 in CH 2 Cl 2 resulted in the rapid formation of 15 according to the 1 H and 31 P NMR parameters, close to those described for similar palladium-containing dendrimers …”

Dendrimers Containing Two Metallic Layers. Chloride Migration from Peripheral Gold, Palladium, or Rhodium Metals to Internal Ruthenium Atoms

“…Dendrimer 3 was used as starting material. The reaction of 3 with [PdCl(η 3 -2-MeC 3 H 4 )] 2 in CH 2 Cl 2 resulted in the rapid formation of 15 according to the 1 H and 31 P NMR parameters, close to those described for similar palladium-containing dendrimers …”

Dendrimers Designed for Functions: From Physical, Photophysical, and Supramolecular Properties to Applications in Sensing, Catalysis, Molecular Electronics, Photonics, and Nanomedicine

“…The dendrimer was less stable than the monomer under batch conditions, which could be taken into account by the flexibility of the dendrimer tethers. 900 Similar results were obtained with diphenyl- 901 or phenyl(aryl)phosphine-terminated carbosilane dendrimers, 902 with the dendrimers being less active than the monomer, although these catalysts were more active than those with the P,O ligands above. Interestingly, with a P-stereogenic phosphine, the cationic catalyst, as a BF 4…”

Carbosilane Dendrimers Peripherally Functionalized with P-Stereogenic Monophosphines. Catalytic Behavior of Their Allylpalladium Complexes in the Asymmetric Hydrovinylation of Styrene

“…Allylpalladium Compounds [PdCl( η 3 -2-Me-C 3 H 4 )( n P 1 )] ( n = 1 − 3) and [PdCl( η 3 -2-Me-C 3 H 4 )( n P 2 )] ( n = 1, 2). The grafting of the Pd(η 3 -2-MeC 3 H 4 )Cl units on the surface of the dendrimers was achieved in good yields by reaction of the dinuclear allyl complex [Pd(μ-Cl)(η 3 -2-MeC 3 H 4 )] 2 with the corresponding phosphine derivatives in CH 2 Cl 2 at room temperature (Scheme ) 2 …”

“…After the AgCl that formed was filtered out, the solution was introduced immediately in the reactor and was pressurized with ethylene. In none of the cases did we try to isolate the precursors (using CH 3 CN as solvent for example), given that previous work in our laboratory with nonchiral palladodendrimers had shown that the compounds stabilized with acetonitrile were less effective in terms of activity . The results shown in Table were obtained as a mean value of at least three runs.…”

Dendrimers Containing Two Metallic Layers. Chloride Migration from Peripheral Gold, Palladium, or Rhodium Metals to Internal Ruthenium Atoms

“…Dendrimer 3 was used as starting material. The reaction of 3 with [PdCl(η 3 -2-MeC 3 H 4 )] 2 in CH 2 Cl 2 resulted in the rapid formation of 15 according to the 1 H and 31 P NMR parameters, close to those described for similar palladium-containing dendrimers …”

Dendrimers Designed for Functions: From Physical, Photophysical, and Supramolecular Properties to Applications in Sensing, Catalysis, Molecular Electronics, Photonics, and Nanomedicine

“…The dendrimer was less stable than the monomer under batch conditions, which could be taken into account by the flexibility of the dendrimer tethers. 900 Similar results were obtained with diphenyl- 901 or phenyl(aryl)phosphine-terminated carbosilane dendrimers, 902 with the dendrimers being less active than the monomer, although these catalysts were more active than those with the P,O ligands above. Interestingly, with a P-stereogenic phosphine, the cationic catalyst, as a BF 4…”

Carbosilane Dendrimers Peripherally Functionalized with P-Stereogenic Monophosphines. Catalytic Behavior of Their Allylpalladium Complexes in the Asymmetric Hydrovinylation of Styrene

“…Allylpalladium Compounds [PdCl( η 3 -2-Me-C 3 H 4 )( n P 1 )] ( n = 1 − 3) and [PdCl( η 3 -2-Me-C 3 H 4 )( n P 2 )] ( n = 1, 2). The grafting of the Pd(η 3 -2-MeC 3 H 4 )Cl units on the surface of the dendrimers was achieved in good yields by reaction of the dinuclear allyl complex [Pd(μ-Cl)(η 3 -2-MeC 3 H 4 )] 2 with the corresponding phosphine derivatives in CH 2 Cl 2 at room temperature (Scheme ) 2 …”

“…After the AgCl that formed was filtered out, the solution was introduced immediately in the reactor and was pressurized with ethylene. In none of the cases did we try to isolate the precursors (using CH 3 CN as solvent for example), given that previous work in our laboratory with nonchiral palladodendrimers had shown that the compounds stabilized with acetonitrile were less effective in terms of activity . The results shown in Table were obtained as a mean value of at least three runs.…”

Dendrimers Containing Two Metallic Layers. Chloride Migration from Peripheral Gold, Palladium, or Rhodium Metals to Internal Ruthenium Atoms

“…Dendrimer 3 was used as starting material. The reaction of 3 with [PdCl(η 3 -2-MeC 3 H 4 )] 2 in CH 2 Cl 2 resulted in the rapid formation of 15 according to the 1 H and 31 P NMR parameters, close to those described for similar palladium-containing dendrimers …”

Dendrimers Designed for Functions: From Physical, Photophysical, and Supramolecular Properties to Applications in Sensing, Catalysis, Molecular Electronics, Photonics, and Nanomedicine

“…The dendrimer was less stable than the monomer under batch conditions, which could be taken into account by the flexibility of the dendrimer tethers. 900 Similar results were obtained with diphenyl- 901 or phenyl(aryl)phosphine-terminated carbosilane dendrimers, 902 with the dendrimers being less active than the monomer, although these catalysts were more active than those with the P,O ligands above. Interestingly, with a P-stereogenic phosphine, the cationic catalyst, as a BF 4…”

Carbosilane Dendrimers Peripherally Functionalized with P-Stereogenic Monophosphines. Catalytic Behavior of Their Allylpalladium Complexes in the Asymmetric Hydrovinylation of Styrene

“…Allylpalladium Compounds [PdCl( η 3 -2-Me-C 3 H 4 )( n P 1 )] ( n = 1 − 3) and [PdCl( η 3 -2-Me-C 3 H 4 )( n P 2 )] ( n = 1, 2). The grafting of the Pd(η 3 -2-MeC 3 H 4 )Cl units on the surface of the dendrimers was achieved in good yields by reaction of the dinuclear allyl complex [Pd(μ-Cl)(η 3 -2-MeC 3 H 4 )] 2 with the corresponding phosphine derivatives in CH 2 Cl 2 at room temperature (Scheme ) 2 …”

“…After the AgCl that formed was filtered out, the solution was introduced immediately in the reactor and was pressurized with ethylene. In none of the cases did we try to isolate the precursors (using CH 3 CN as solvent for example), given that previous work in our laboratory with nonchiral palladodendrimers had shown that the compounds stabilized with acetonitrile were less effective in terms of activity . The results shown in Table were obtained as a mean value of at least three runs.…”