This report reviews the role of palladium dendrimers in catalysis as (a) soluble macromolecules for support catalysts, that are separable by nanofiltration techniques; (b) ligand-modifiers can create specific metal nanoenvironments and tune solubility catalyst; (c) spacers molecular catalysts proportionate a more homogeneous-like environment to supported catalytic sites; (d) precursors synthesis mono- bimetallic nanoparticles controlled size narrow distribution. Some examples with related...

Abstract Controlling the synthesis of stable metal nanoparticles in water is a current challenge nanochemistry. The strategy presented herein uses sulfonated N‐heterocyclic carbene (NHC) ligands to stabilize platinum (PtNPs) water, under air, for an indefinite time period. particles were prepared by thermal decomposition preformed molecular Pt complex containing NHC ligand and then purified dialysis characterized TEM, high‐resolution spectroscopic techniques. Solid‐state NMR studies showed...

Abstract Novel amine‐ or ammonium‐terminated carbosilane dendrimers of type n G‐[Si{OCH 2 (C 6 H 3 )‐3,5‐(OCH CH NMe ) }] x , G‐[Si{O(CH N(Me)(CH and G‐[Si{(CH NH + I − Cl have been synthesized characterized up to the third generation by two strategies: 1) alcoholysis SiCl bonds with amino alcohols subsequent quaternization MeI, 2) hydrosilylation allylamine SiH dendritic systems HCl. Quaternized are soluble in water, although degradation is apparent due hydrolysis SiO bonds. However,...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT{[2-(Dimethylamino)ethyl]cyclopentadienyl}trichlorotitanium: A New type of Olefin Polymerization CatalystJuan Carlos Flores, James C. W. Chien, and Marvin D. RauschCite this: Organometallics 1994, 13, 11, 4140–4142Publication Date (Print):November 1, 1994Publication History Published online1 May 2002Published inissue 1 November 1994https://pubs.acs.org/doi/10.1021/om00023a006https://doi.org/10.1021/om00023a006research-articleACS PublicationsRequest...

The synthesis and characterization of new water-soluble platinum(0) complexes bearing sulfonated N-heterocyclic carbene (NHC) divinyltetramethylsiloxane (dvtms) ligands are described. These complexes, the general formula (NHC)Pt(dvtms), active recyclable catalysts for hydrosilylation phenylacetylene other alkynes at room temperature in water. Our findings indicate that NHC–Pt(0) bonds reasonably stable under these catalytic conditions, although hydrolysis is observed temperatures above 80 °C pure

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT[N,N'-Bis(trimethylsilyl)benzamidinato]titanium and -zirconium Compounds. Synthesis Application as Precursors for the Syndiospecific Polymerization of StyreneJuan C. Flores, James W. Chien, Marvin D. RauschCite this: Organometallics 1995, 14, 4, 1827–1833Publication Date (Print):April 1, 1995Publication History Published online1 May 2002Published inissue 1 April...

Dendrimers provide new and practical solutions to the complex problem of catalyst separation from product stream. functionalized with active metal complexes are themselves soluble, nanosized catalysts that capable combining high activity selectivity classical homogeneous enhanced capabilities added by macromolecule. This report reviews recovery recycling metallodendrimer different techniques, such as nanofiltration, precipitation, or immobilization on solid supports, use appropriate solvent...

A series of carbosilane dendritic compounds Gn-ONNMem, containing one (n = 0), four 1), eight 2), or 16 3) terminal pyridylimine ligands, substituted with m methyl groups (m 0, 2, 3), and nickel complexes Gn-ONNMemNiBr2, comprising monometallic to metallodendritic structures, have been synthesized. The complexes, in combination methylaluminoxane (MAO), are active catalysts for the concurrent transformation ethylene into mixtures toluene-insoluble polyethylene oily oligomers. Oligomers...

This report describes the synthesis of water-soluble silver(I) and platinum(II) complexes bearing sulfonated mono- or dianionic N-heterocyclic carbene ligands. Thus, treatment corresponding zwitterionic imidazolium derivative with oxide in water afforded light-sensitive bis(carbene) Ag[Ag(NHC)2] (2Ag+), which were transformed into stable salts Na[Ag(NHC)2] (2) by addition sodium chloride. In contrast, same reaction dmso mono(carbenes) general formula Na[AgCl(NHC)] (3). The solvent-dependence...

Thanks to new water-soluble Ru nanoparticles (NPs) stabilized by sulfonated NHC ligands, we demonstrate that it is possible monitor the catalyst/substrate interaction using NMR chemical shift perturbations (CSPs), under conditions closely resemble those applied during enantiospecific C-H deuteration of l-lysine. Correlating pH dependence l-lysine with surface RuNPs and its subsequent deuteration, our study underscores importance oriented binding as a critical factor for H/D exchange.

Abstract A synthetic strategy has been developed for the preparation of new peripheral amine‐ or ammonium‐terminated carbosilane dendrimers type n G‐[Si(OCH 2 CH NMe ) y ] x 3 + I – , respectively. It consists alcoholysis well‐known chlorosilane‐terminated with N ‐dimethylethanolamine and subsequent quaternization MeI. All these systems are susceptible to hydrolysis, although decomposition depends on concentration dendrimer generation. Evaluation toxicities by phase‐contrast light microscopy...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT(N,N'-Dimethyl-p-toluamidinato)trichlorotitanium: Synthesis, Structure, and Polymerization CatalysisJuan C. Flores, James W. Chien, Marvin D. RauschCite this: Organometallics 1995, 14, 4, 2106–2108Publication Date (Print):April 1, 1995Publication History Published online1 May 2002Published inissue 1 April 1995https://pubs.acs.org/doi/10.1021/om00004a073https://doi.org/10.1021/om00004a073research-articleACS PublicationsRequest reuse...

Abstract Controlling the synthesis of stable metal nanoparticles in water is a current challenge nanochemistry. The strategy presented herein uses sulfonated N‐heterocyclic carbene (NHC) ligands to stabilize platinum (PtNPs) water, under air, for an indefinite time period. particles were prepared by thermal decomposition preformed molecular Pt complex containing NHC ligand and then purified dialysis characterized TEM, high‐resolution spectroscopic techniques. Solid‐state NMR studies showed...

A series of monocyclopentadienyltitanium complexes containing the 1-(2-phenylethyl)-2,3,4,5-tetramethylcyclopentadienyl ligand (C5Me4CH2CH2Ph) have been synthesized and characterized. The reaction C5Me4(SiMe3)CH2CH2Ph (2) with TiCl4 was used to trichloro complex (C5Me4CH2CH2Ph)TiCl3 (3), molecular structure which confirmed by an X-ray diffraction study. Compound 3 further converted into (C5Me4CH2CH2Ph)TiMe3 (4). Reaction latter 1 equiv [Ph3C][B(C6F5)4] almost quantitative give "cationic"...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMonocyclopentadienyl-type titanium complexes with the [.eta.5-.eta.5-(C5H4)2SiMe2]2- ligand. X-ray crystal structure of [(TiCl)2(.mu.2-O){.mu.2-.eta.5-.eta.5-(C5H4)2SiMe2}]2(.mu.2-O)2. The first example a nonplanar oxide ["Ti4O4"] coreSantiago Ciruelos, Tomas Cuenca, Juan Carlos Flores, Rafael Gomez, Pilar Gomez-Sal, and Pascual RoyoCite this: Organometallics 1993, 12, 3, 944–948Publication Date (Print):March 1, 1993Publication History Published...

Carbosilane dendrimers Gn-[(ONNMe2)NiBr2]m, containing up to sixteen terminal pyridylimine nickel complexes, have been studied as catalysts for polymerization of ethylene; the microstructure and oligomer/polymer distribution are significantly affected by generation dendritic precursor.

Series of neutral and cationic palladium carbosilane dendritic compounds the general formula Gn-ONNMem[Pd(X)Y] (X, Y = Cl; X Me, MeCN), containing 4 (n 1), 8 2) or 16 3) terminal pyridylimine complexes, substituted with m methyl groups (m 0, 2, 3), along corresponding monometallic counterparts 0), have been synthesized. Monometallic chloro consist a cis/trans mixture diastereoisomers, compositions according to their electronic steric features. The Gn-ONNMem[PdMe(MeCN)]+ are found be active...

Treatment of [Ti(C5H5)Cl3] with 4-allyl-2,6-dimethoxyphenol (II) gave the corresponding aryloxy complex [Ti(C5H5){OC6H2(OMe)2(C3H5)}Cl2] (2), while hydrosilylation reactions allyl group 4-allyl-2-methoxyphenol (eugenol; I) or HSiEt3 and subsequent reaction led to mononuclear compounds [Ti(C5H5){OC6H4-n(OMe)n(C3H6SiEt3)}Cl2] (n = 1 (3), 2 (4)) in high yield. This synthetic procedure has been used as a model for preparation new peripheral carbosilane metallodendrimers. Series dendrimer...

{[2-(dimethylamino)ethyl]cyclopentadienyl}titanium trichloride (CpNTiCl3, 1) was activated with methylaluminoxane (MAO) to catalyze polymerizations of ethylene (E), propylene (P), ethylidene norbornene (ENB), vinylcyclohexene (VCH), and 1,4-hexadiene (HD). The dependence homopolymerization activity (A) 1/MAO on olefin concentration ([M]n) is n = 2.0 ± 0.5 for E 1.8 0.2 P. value 2.4 CpTiCl3/MAO catalysis polymerization; this system does not polymerize propylene. catalyzes HD polymerization at...

[2-(Dimethylamino)ethyl]-substituted cyclopentadienyltitanium complexes (3−6) have been synthesized and characterized. Structural data indicates intramolecular coordination of the dimethylamino group to titanium. The catalytic activities selectivities for styrene, ethylene, propylene polymerization with 3−6 compared reference compounds CpTiCl3 (1), Cp*TiCl3 (2), Cp2TiCl2 (7), are consistent Ti−N Lewis acid−base interaction.

This paper describes the synthesis of a series titanium and zirconium metallocenes bearing one or two first-generation silane dendritic wedges as bulky substituents at their cyclopentadienyl rings. Wedges (R2R′SiCH2CH2)3SiCl [R = R′ Et (1); R Ph, Me (2)] were prepared by hydrosilylation chlorotrivinylsilane with R2R′SiH. They reacted K(C5H5) and, subsequently, KH to give K[(R2R′SiCH2CH2)3Si(C5H4)] (3); (4)]. The dendronized cyclopentadienides 3 4 starting materials for preparation mixed-ring...

A series of water-soluble (NHC)Pt(0)(dvtms) and (NHC)Pt(0)(AE) complexes containing different sulfonated NHC ligands (dvtms = divinyltetramethyldisiloxane AE diallyl ether) are reported. The dvtms compounds have been found to be quite robust display some conformational rigidity, whereas their counterparts less stable more flexible. catalytic evaluation these in the hydrosilylation alkynes water revealed no benefits favor labile spectator diene (AE), a fairly regular behavior for all that...

Abstract A series of mono‐ and dendritic trimetallic PEPPSI‐type (pyridine‐enhanced precatalyst preparation stabilization initiation) complexes bearing N‐heterocyclic carbene (NHC) ligands containing a protected amine in the form an ethylphthalimido group have been synthesized. These discrete prototypes covalently bound to suitable supports studied Mizoroki–Heck coupling aryl iodides under mild conditions, including sets experiments assess lifetime active species. The palladated dendrons are...

A family of water-soluble dimethyl complexes formula cis-[PtMe2(dmso)(NHC·Na)] (2), in which NHC is an anionic N-heterocyclic carbene bearing a sulfonatopropyl chain on one the nitrogen atoms and (a), methyl (b), mesityl (c), or 2,6-diisopropylphenyl group (d) other, have been prepared. The hydrolytic stability Pt–C bonds these under different neutral, alkaline, acidic aqueous conditions has also studied. Complexes 2 were found to be quite stable at room temperature water neutral alkaline...