Water-soluble Phosphine Complexes Research Articles

Aqueous organometallic chemistry: the mechanism of catalytic hydrogenations with chlorotris(1,3,5-triaza-7-phosphaadamantane) rhodium(I)

Abstract The water-soluble phosphine complex of Rh(I), RhCl(PTA) 3 ( 1 ) was shown to be an active catalyst for the hydrogenation of various olefinic and oxo-acids, as well as of allyl alcohol and 4-sulfostyrene in aqueous solution under mild conditions. Detailed kinetic investigations were carried out with crotonic acid and allyl alcohol as substrates. The rate of hydrogenation of both compounds showed a sharp maximum as a function of pH at 4.7. Hydrogenation of itaconic, crotonic and α-acetamidocinnamic acid in D 2 O led to 45–100% deuteration of the products with 25–100% stereoselectivity towards the α-carbon atom. These results, together with those of pH-static hydrogenation of complex 1 , suggest that water strongly assists the dehydrochlorination of 1 to yield the catalytically active monohydrido species HRh(PTA) 3 ( 2 ). Nevertheless, depending on the substrate and the pH of the solution the dihydridic pathway may remain partially operative.

Water-soluble organometallic compounds. 5. The regio-selective catalytic hydrogenation of unsaturated aldehydes to saturated aldehydes in an aqueous two-phase solvent system using 1,3,5-triaza-7-phosphaadamantane complexes of rhodium

The water-soluble phosphine complex of Rh(I), [Rh(PTAH)(PTA)2Cl]Cl(1), has been synthesized from RhCl3 and 1,3,5,-triaza-7-phosphaadamantane (PTA) in 96% ethanol. This complex is an effective catalyst for the regioselective reduction of unsaturated aldehydes to saturated aldehydes. The rate of hydrogenation of trans-cinnamaldehyde with sodium formate as reductant was studied as a function of catalyst, substrate, and sodium formate concentration. The presence of an excess of PTA was found to inhibit hydrogenations completely. This reaction was also found to be partially inhibited by cyclo-octatetraene and Hg(0), leading to the conclusion that both heterogenous and homogenous mechanisms are operating. Recycling experiments show complex 1 to be quite robust, with minimal leaching into the organic phase in a biphasic system. The complex resulting from the addition of an excess of PTA to 1, [Rh(PTAH)3(PTA)Cl]Cl3 (2) has been prepared and structurally characterized by a single crystal X-ray diffraction study. 31P and 1H NMR, IR and UV-VIS spectroscopy and pH titrametric measurements were employed to study the reactivity of the various rhodium PTA complexes in aqueous solutions.

パラジウム‐水溶性ホスフィン錯体による二相系触媒反応

Water-soluble complex catalysts are useful because of simple separation from the products, high activity, and selectivity. To conduct palladium-catalyzed reactions under liquid-liquid two-phase conditions, water-soluble polyether- or crown ether-substituted phosphines with phase transfer ability have been synthesized and characterized. The following reactions in aqueous media catalyzed by the water-soluble phosphine complexes of palladium are surveyed. (1) Hydrogenolysis of allylic halides with formate proceeds smoothly under liquid-liquid or liquid-solid two-phase conditions and 1-olefins are formed. In the two-phase catalysis the palladium complex itself plays a role of a phase transfer agent and a mechanism of inverse phase transfer process has been proposed. Benzylic halides are reduced similarly. (2) Allylic and benzylic halides are carbonylated under atmospheric pressure in aqueous NaOH/organic solvent system to afford β, γ-unsaturated acid and phenylacetic acid, respectively. (3) The reaction of bromoarenes possessing electron-withdrawing groups with ethylene (the Heck reaction) is also possible in an aqueous phase.

Stability and Reactivity of Dihydroxobis(trimethylphosphine)platinum(II), an Intermediate Species for the Synthesis of a Variety of Water-Soluble Phosphine Complexes

Abstract A dihydroxoplatinum(II) compound, cis-[Pt(OH)2(PMe3)2]·nH2O (Me = methyl, n = 2–3; 1), has been characterized by 31P, 195Pt, 13C, and 1H NMR spectroscopy. The thermal stability of 1 was examined. The presence of several water molecules is required for the stabilization of 1. The solution equilibria and the reaction of 1 with aqueous hydrogen peroxide were observed by 31P NMR spectroscopy. The neutralization of 1 with several dicarboxylic acids afforded water-soluble phosphine complexes in quantitative yields. Exposure of 1 toward air gives the carbonatoplatinum(II), cis-[Pt(CO3)(PMe3)2]·2H2O. Its crystal structure determination has revealed that the carbonate anion forms four-membered ring with a platinum atom.

Water-soluble organometallic compounds. 2. Catalytic hydrogenation of aldehydes and olefins by new water-soluble 1,3,5-triaza-7-phosphaadamantane complexes of ruthenium and rhodium

The authors describe the chemical preparation of water-soluble phosphine complexes of ruthenium (II) and rhodium (I). The complex RuCl{sub 2}(PTA){sub 4} (2a) and its protonated analog RuCl{sub 2}(PTA){sub 4}{center_dot} 2HCl (2b) and the cis-bis-(phosphine) complex RhCl(PTA){sub 2}{center_dot} 2HCl, derived form the protonation of RhCl(PTA){sub 3} by HCl were characterized by X-ray crystallography. 2a is catalytically active for the conversion of unsaturated aldehydes to unsaturated alcohols and RhCl(PTA){sub 3} catalyzes olefin hydrogenation. 14 refs., 2 figs., 1 tab.

Organometallic catalysis in aqueous solutions: the biphasic transfer hydrogenation of aldehydes catalyzed by water-soluble phosphine complexes of ruthenium, rhodium and iridium

Aromatic and aliphatic aldehydes can be reduced to the corresponding alcohols by hydrogen transfer from formate using, as catalysts, water-soluble complexes of Ru(II), Rh(I) and Ir(I) with monosulphonated triphenylphosphine (mSPφ)2, in aqueous/organic biphasic systems without phase transfer catalysts. HRu(O2CH)(mSPφ)2)3 was identified as the key intermediate in the processes catalyzed by RuCl2(mSPφ2)2 in an excess of phosphine. Olefinic double bonds (including those in α,β-unsaturated aldehydes), as well as substitutents of the aromatic ring, are not affected. Attempted catalysis of the transfer of benzaldehyde from the organic to the aqueous phase by β-cyclodextrin resulted in inhibition of the metal complex-catalyzed transfer hydrogenation.

“Counter” Phase Transfer Catalysis by Water-soluble Phosphine Complexes. Catalytic Reduction of Allyl Chlorides and Acetates with Sodium Formate in Two-phase Systems

Abstract In the reduction of allyl chlorides and acetates with sodium formate in a heptane-water two-phase system, water-soluble palladium complexes function as a novel type of catalyst which transports the substrate into the aqueous phase and causes it to react with sodium formate.

ChemInform Abstract: CATALYSIS BY WATER‐SOLUBLE PHOSPHINE COMPLEXES OF TRANSITION METAL IONS IN AQUEOUS AND TWO‐PHASE MEDIA

Chemischer InformationsdienstVolume 12, Issue 42 Reviews ChemInform Abstract: CATALYSIS BY WATER-SOLUBLE PHOSPHINE COMPLEXES OF TRANSITION METAL IONS IN AQUEOUS AND TWO-PHASE MEDIA F. JOO, F. JOOSearch for more papers by this authorZ. TOTH, Z. TOTHSearch for more papers by this author F. JOO, F. JOOSearch for more papers by this authorZ. TOTH, Z. TOTHSearch for more papers by this author First published: October 20, 1981 https://doi.org/10.1002/chin.198142343AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue42October 20, 1981 RelatedInformation

Catalysis by water-soluble phosphine complexes of transition metal ions in aqueous and two-phase media

Abstract The chemistry of water-soluble tertiary phosphine complexes in aqueous solution appears to be very similar to that of their counterparts in non-aqueous media. Neither the effect of protons, nor the presence of an excess of a potential ligand: water, cause dramatic changes in the activation of certain small molecules (H2, CO, HCN). However, when electrostatic interactions are important, water, as the solvent, may strongly influence the outcome of the reaction. When the reactions are carried out in two-phase aqueous/organic solvent systems, the water-soluble catalysts can be relatively easily recirculated.

Formation and catalytic properties of water-soluble phosphine complexes

Using sulfonated triphenylphosphine, a number of water-soluble platinum metal — phosphine complexes were prepared. Some of them show a pronounced reactivity towards small molecules and the ruthenium compound catalyzes the hydrogenation of ketocarboxylic acids.