Phosphine Groups Research Articles

Fe and Co Complexes of Rigidly Planar Phosphino-Quinoline-Pyridine Ligands for Catalytic Hydrosilylation and Dehydrogenative Silylation

Co and Fe dihalide complexes of a new rigidly planar PNN ligand platform are prepared and examined as precatalysts for hydrosilylation of alkenes. Lithiation of Thummel’s 8-bromo-2-(pyrid-2′-yl)quinoline followed by treatment with (i-Pr)2PCl and (C6F5)2PCl afforded the phosphine-quinoline-pyridine ligands, abbreviated RPQpy for R = i-Pr and C6F5, respectively. These ligands form 1:1 adducts with the dichlorides and dibromides of iron and cobalt. Crystallographic characterization of FeBr2(iPrPQpy), FeBr2(ArFPQpy), CoCl2(iPrPQpy), CoBr2(iPrPQpy), and CoCl2(ArFPQpy) confirmed that the M–P–C–C–N–C–C–N portion of these complexes is planar within 0.078 A unlike previous generations of PNN complexes where deviations from planarity were ∼0.35 A. Bond distances as well as magnetism indicate that the Fe complexes are high spin and the cobalt complexes are high spin or participate in spin equilibria. Also investigated were the NNN analogues of the RPQpy ligands, wherein the phosphine group was replaced by the mesity...

Nonadiabatic dynamics simulations on internal conversion and intersystem crossing processes in gold(i) compounds.

The position at which the second gold(i)-phosphine group is attached was experimentally found to play a noticeable role in intersystem crossing rates of gold(i) naphthalene derivatives. However, the physical origin is ambiguous. Herein we have employed generalized trajectory-based surface-hopping dynamics simulations to simulate the excited-state relaxation dynamics of these gold(i) naphthalene compounds including both the intersystem crossing process from the initially populated first excited singlet states S1 to triplet manifolds and internal conversion processes within these triplet states. Our predicted intersystem crossing rates are consistent with experiments very well. On the basis of the present results, we have found that (1) ultrafast and subpicosecond intersystem crossing processes are mainly caused by small energy gaps and large spin-orbit couplings between S1 and Tn; (2) adding the second gold(i)-phosphine group does not increase spin-orbit couplings between S1 and Tn but decrease their values remarkably, which implies that heavy-atom effects are state-specific, not state-universal; (3) the position at which the second gold(i)-phosphine group is attached has a remarkable influence on the electronic structures of S1 and Tn and their relative energies, which affect energy gaps and spin-orbit couplings between S1 and Tn and eventually modulate intersystem crossing rates from S1 to Tn. These new insights are very useful for the design of gold-containing compounds with excellent photoluminescence properties. Finally, this work also exemplifies that different isomers of a compound could have distinct excited-state relaxation dynamics.

Preparation and application of phosphinic acid functionalized nanosilica for the effective removal of mercury (II) in aqueous solutions

A novel adsorbent was synthesized by functionalizing nanosilica with phosphinic acid groups for the removal of mercury ions from aqueous solutions. The synthesized absorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Meanwhile, the effects of initial pH, contact time and initial mercury ions concentration on the removal of mercury ions from aqueous solutions were investigated by batch adsorption experiments. The results showed that the removal rate reached 99.11% and the maximum adsorption capacity was up to 274.32 mg/g at pH 2 and the equilibrium time of adsorption was about 1 h. The absorbent presented good selectivity for mercury ions among Zn(II), Ni(II), Mn(II) and Ge(IIII). Moreover, the obtained adsorbent has good reusability and the absorbability decreased only from 98.76 to 94.75% after five cycles. Besides, the adsorption isotherms fitted well to the Langmuir isotherm model and adsorption kinetics followed the pseudo-second-order model. The removal mechanism of mercury via phosphinic acid-functionalized silica nanoparticles was chelation interaction. All the experimental data indicated that the phosphinic acid-functionalized silica nanoparticles are very promising in removal of mercury ions from aqueous solutions.

Amino-P Ligands from Iminosugars: New Readily Available and Modular Ligands for Enantioselective Pd-Catalyzed Allylic Substitutions

The construction of a novel class of amino-phosphite/phosphinite/phosphine ligands containing a protected pyrrolidine-3,4-diol moiety is presented. These ligands are obtained from readily available sugars. They thus contain the advantages of carbohydrates in terms of selection of the stereogenic carbons, polyfunctional groups able to modulate the electronic and steric properties, and the general good stability of carbohydrate derivatives. They constitute a novel class of P,N-ligands that have been used in the enantioselective allylic substitutions of acyclic and cyclic substrates with varied electronic and steric requirements, using different C- and N-nucleophiles, with high enantioselectivities. Among the three groups of P,N-ligands (amino-P; P = phosphite, phosphinite, and phosphine groups) the new amino-phosphite ligands give the widest substrate and nucleophile scope, including the more challenging hindered linear and cyclic substrates. In particular, for carbohydrate-derived amino-phosphite ligands a...

Palladium(II) complexes with new bidentate phosphine-imine ligands for the Suzuki C[sbnd]C coupling reactions in supercritical carbon dioxide

Newly designed perfluorinated phosphine-imine ligands (3a-c) have been synthesized from the 3-(heptadecafluorooctyl)aniline and 2-(diaryl)phosphinobenzaldehyde (diaryl: −Ph2, 2a; −(3,5-(CH3)2Ph)2, 2b; −(3,5-(CF3)2Ph)2, 2c) and complexed with dichloro(1,5-cyclooctadiene)palladium(II) to form supercritical carbon dioxide (ScCO2) soluble palladium(II) complexes (4a-c). All compounds were fully characterized using spectroscopic and analytical techniques, including 31P, 1H, 19F, 13C NMR and FTIR spectroscopies and high resolution mass spectroscopy. These palladium(II) complexes having perfluoroctyl ponytails (-C8F17) are soluble in carbon dioxide at >333 K under 122 atm of CO2 pressure. Homogenous palladium catalyzed Suzuki CC coupling reactions using the novel catalysts were carried out at 353 K 135 atm. To the best of our knowledge, we applied the first example of hetereodonor bidentate ligands which are bearing both phosphine and imine group for the palladium catalyzed Suzuki CC coupling reaction in ScCO2 solvent system.

Synthesis, Application and Kinetic Studies of Chiral Phosphite‐Oxazoline Palladium Complexes as Active and Selective Catalysts in Intermolecular Heck Reactions

AbstractThis study identifies new phosphite‐oxazoline ligands that have been successfully applied in the palladium‐catalyzed intermolecular asymmetric Heck reaction. The design of the new phosphite‐oxazoline ligands derives from a previous successful generation of phosphine‐oxazoline ligands, by replacing the phosphine group with several π‐acceptor biaryl phosphite moieties. With these simple modifications, the new phosphite‐based ligands, unlike previous phosphine‐oxazoline, not only present a modular design with numerous potential phosphite groups available, but they are also air‐stable solids, which can be made in the same number of synthetic steps as the phosphine analogues. The substitution of the phosphine by a biaryl phosphite group extended the range of substrates and triflates sources that can be coupled with regio‐, enantioselectivities and activities comparable to the few best ones reported. In addition, the ligands that provided the best selectivities contained an isopropyl oxazoline moiety instead of the tert‐butyl group found in the related phosphine‐oxazoline ligands, which is made from a much more expensive precursor. In this paper we have also carried out kinetic studies and a Hammett plot analysis to determine the rate determining step of this system in the regime of interest. We suggest a likely explanation for the fast Heck reaction of the phosphite‐oxazoline catalysts.magnified image

On the Variable Reactivity of Phosphine-Functionalized [Ge9 ] Clusters: Zintl Cluster-Substituted Phosphines or Phosphine-Substituted Zintl Clusters.

The reaction of [(Ge9 {Si(TMS)3 }2 PtBu2 )]- with NHCMes CuCl yields [(Ge9 {Si(TMS)3 }2 )(tBu2 P)]Cu(NHCMes ) (1), which is a new derivative of the recently reported monomeric zwitterionic tetrel cluster compounds [(Ge9 {Si(TMS)3 }2 )(tBu2 P)]M(NHCDipp ) (M: Cu, Ag, Au). By contrast, the reaction of the same anion [(Ge9 {Si(TMS)3 }2 PtBu2 )]- with the more labile copper phosphine complex Cy3 PCuCl leads to the formation of [Ge9 {Si(TMS)3 }2 {(tBu)2 PCu}2 Ge9 {Si(TMS)3 }2 ] (2), which is a neutral dimeric twofold-bridged [Ge9 ] cluster compound, with the exo-bonded phosphine substituent being involved in the cluster bridging. In case of the presence of sterically more demanding phosphines in [Ge9 {Si(TMS)3 }2 PR2 ]- [R: Mes (3) and NiPr2 (4)], reactions with NHCDipp CuCl yielded the complexes NHCDipp Cu[η3 -Ge9 {Si(TMS)3 }2 (PR2 )] [R: Mes (5) and NiPr2 (6)], comprising exclusively Cu-Ge bonds. Compounds 5 and 6 show varying reactivity in dependence of the identity of the phosphine group and represent the first examples of fourfold-substituted [Ge9 ] clusters with three different ligands bound to the [Ge9 ] cluster core. All compounds were characterized by 1 H, 13 C, 31 P, and 29 Si NMR spectroscopy. Additionally, compounds 3 and 4 were analyzed by ESI-MS, and the structures of compounds 1, 2, and 5 were characterized by single-crystal X-ray diffraction.

PONy Dyes: Direct Addition of P(III) Nucleophiles to Organic Fluorophores.

Nucleophilic addition of phosphinic acid, phosphites, sodium dialkyl phosphites, phosphoramidites, phosphinites, and phosphonites to highly polarized or cationic fluorophores, followed by oxidation, results in new "PONy" dyes with auxochromic phosphinate, phosphonate, or phosphonamidate groups. The reaction was applied to a wide variety of coumarins, (thio)pyronins, and N-alkylacridinium and 5,6-dihydrobenzo[c]xanthen-12-ium salts as well as a meso-chlorinated BODIPY to provide compact dyes with red-shifted absorption and emission bands and Stokes shifts up to 8200 cm-1.

The Influence of Stepwise P-Oxidation on the Coordination and Redox Behavior of W–Bisphosalkyne Complex Ligands

The terminal phosphine groups at the tungsten bisphosphine alkyne complex [Tp*W(CO)(I)(η2-C,C′-Ph2PC2PPh2)] (2) {Tp* = hydridotris(3,4,5-trimethylpyrazolyl)borate} were selectively oxidized by common methods to form the alkyne complexes 2EE (E = O, S) with either two phosphine oxide or two phosphine sulfide substituents. The respective mono-oxidized analogues 2E (E = O, S) were obtained by subjecting the already oxidized intermediates [Tp*W(CO)(I)(η2-C,C′-Ph2P(E)C2H)] 1E (E = O, S) to a late-stage phosphine introduction at the complex template. These modulations of the peripheral alkyne moiety have a clear impact on the redox potential of the metal-based oxidation altering the W(II/III) potential by +0.1 V on average per oxidized phosphine. In contrast to the comparable redox behavior of 2O and 2S, the coordination behavior of these complex ligands differs substantially. XRD studies show that complex 2 and the sulfide 2S act either as a P,P’- or P,S-chelate ligand leading to the dinuclear complexes [(2)Pd...

The trans Effect in Palladium Phosphine Sulfonate Complexes.

Palladium phosphine sulfonate complexes constitute an efficient family of catalysts for both homopolymerization of ethylene and copolymerization of ethylene with a number of polar monomers. Their catalytic mechanisms have been extensively studied but not fully understood at the electronic structure level. The energy decomposition analysis, complemented with the inspection of the natural orbitals for chemical valence, reveals that their catalytic activity can be rationalized in terms of the so-called trans effect. Furthermore, our analysis shows that the competition for the σ donation of the two ligands PMe3 and L, of the palladium phosphine sulfonate complexes, to the same orbital of Pd in the trans isomer and to different orbitals in the cis isomer is the origin of the trans effect. Although the dominance of the phosphine group prevents an efficient interaction of the ligand L with the Pd atom, the large stabilization gained by the phosphine group renders a very stable trans complex.

Chemists carry out a structural do over

In what is being called an honest mistake, a research group has reported that the structure of the headline compound from a paper it published in 2002 is incorrect. To set the record straight, the team has retracted the paper and at the same time published a new paper reporting the actual structure. The original paper published by Chris Orvig and his group at the University of British Columbia reported the synthesis of a new tetraazamacrocycle ligand (Inorg. Chem. 2002, DOI: 10.1021/ic010716a). The researchers made the compound to see how replacing two methylene groups in a macrocyclic ring with phosphinate groups affected the stability of complexes formed with lanthanide ions. Such complexes are of interest as contrast agents for magnetic resonance imaging. Orvig says all the characterization data were consistent with the ligand having a dimeric structure. But the team had a hard time growing crystals of the ligand and

Asymmetric Transfer Hydrogenation of Ketones Using New Iron(II) (P‐NH‐N‐P′) Catalysts: Changing the Steric and Electronic Properties at Phosphorus P′

AbstractThe asymmetric transfer hydrogenation (ATH) of ketones is an efficient method for producing enantio‐enriched alcohols which are used as intermediates in a variety of industrial processes. Here we report the synthesis of new iron ATH precatalysts (S,S)‐[FeBr(CO)(Ph2PCH2CH2NHCHPhCHPhNC=CHCH2PR′2)][BPh4] (R′=Et, and ortho‐tolyl (o‐Tol)) where one of the phosphine groups is modified with small alkyl and large aryl substituents to probe the effect of this change on the activity and selectivity of the catalytic system. A simple reversible equilibrium kinetic model is used to obtain the initial TOF and the inherent enantioselectivity S=kR/kS of these catalysts along with those for the previously reported catalysts with R′=Ph and Cy for the ATH of acetophenone. With an increase in the size of the PR′2 group, the TOF goes through a maximum at PPh2 while the S value goes through a maximum of 510 at R′=Cy. The complex with R′=o‐Tol starts with a high S value of 200 but is rapidly changed to a second catalyst with an S value of 28. For the reduction of acetophenone to (R)‐1‐phenylethanol, turnover numbers of up to 5200 and ee up to 98 % were achieved. The chemotherapeutic pharmaceutical precursor (R)‐(3′,5′‐bis(trifluoromethyl))‐1‐phenylethanol is synthesized in up to 95 % ee. Several other alcohols can be prepared in greater than 90 % ee by choosing the precatalyst with the correctly matched steric properties. A hydride complex derived from the catalyst with R′=Cy is characterized by NMR spectroscopy. It is proposed that low concentration trans‐hydride carbonyl complexes with the FeH parallel to the NH of the ligand are the active catalysts in all of these systems.

Coordinating Ability of the Iminophosphorane Group in ortho‐Carborane Derivatives

The coordinating ability of the nitrogen donor atom of C‐carboranyl iminophosphoranes was studied in different ligand systems. The analysis of organotin derivatives of the unsubstituted iminophosphorane I1 (SnMe3I1 and SnClMe2I1) and the comparison with the non‐carboranyl analog (SnClMe2I3), reveals the reduced donor capacity of the nitrogen atom due to the closo‐carborane group. To promote the coordination of this weak donor atom, new phosphine–iminophosphorane ligands (IP1 and IP2), with an extra –PPh2 group on the other cage carbon atom, were synthesized and structurally characterized. The analysis of the products formed by the reaction of these ligands with the metal precursor cis‐[PdCl2(PhCN)2] reveals that the phosphine group promotes the coordination of the iminophosphorane nitrogen atom, yielding (P, N) chelates. However, this coordination mode activates the closo‐carborane ligands towards deboronation, and the complexes evolve to the nido derivatives in response to the polar solvents. The activation is increased by the presence of extra donor groups, like in the tridentate ligand IP2, with an extra thioether group. The deboronation by coordination of (P, N) bidentate carboranyl ligands has never been reported, although it has been studied for other ligands, especially for chelating carboranyl diphosphines.

New pallada- and platinacycle complexes of phosphorus ylide: Synthesis, structural characterization, antioxidant capacity and catalytic behavior towards Mizoroki-Heck reactions

The reactions of α-keto stabilized phosphorus ylide Ph2P(CH2)2PPh2C(H)C(O)C6H4-m-Br (Y) with [MCl2(cod)] (M=Pd or Pt; cod=1,5-cyclooctadiene) in equimolar ratio using dichloromethane as a solvent are reported. These reactions led to the formation of new P, C-chelated pallada- and platinacycle complexes [MCl2(Ph2P(CH2)2PPh2C(H)C(O)C6H4-m-Br)] (M=Pd (C1) and Pt (C2)). Characterization of the obtained compounds was performed by elemental analysis and IR, 1H, 13C, and 31P NMR spectroscopic methods. Also, the unequivocal structures of these complexes were characterized crystallographically. Both structures consist of six-membered rings formed by coordination of the phosphorus ylide (Y) through the phosphine group and the ylidic carbon atom to the metal center. Furthermore, palladacycle C1 was employed as an efficient catalyst in the Mizoroki-Heck coupling reaction of several aryl chlorides and olefins. The coupled products of these reactions were obtained under aerobic conditions in high yields using aqueous DMF as a solvent. Additionally, the antioxidant capacity of the reported compounds with butylated hydroxytoluene (BHT) as standard was evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. Apparently, all synthesized compounds possess strong antioxidant capacity (IC50; 0.584±0.009–0.751±0.003mg/ml).

Tetraphosphines with tetra(biphenyl)silane and -stannane cores as rigid scaffold linkers for immobilized catalysts

The silane Si(p-C6H4-p-C6H4Br)4 and the stannane Sn(p-C6H4-p-C6H4Br)4 have been synthesized and characterized. For the silane a single crystal X-ray structure has been obtained. Tetralithiation of the silane with nBuLi and quenching with the corresponding chlorophosphines gave the tetraphosphines Si(p-C6H4-p-C6H4PR2)4 with (R = Ph, Cy, iPr, tBu). Tetralithiation of Sn(p-C6H4-p-C6H4Br)4 led to cleavage of the Sn-C bonds. Therefore, Sn(p-C6H4-p-C6H4PPh2)4 was synthesized by Br/Li exchange of p-Br-C6H4-p-C6H4PPh2 with nBuLi and reaction with SnCl4. The silanes have been immobilized on silica by generating three phosphonium groups per molecule that were bound to the surface via strong electrostatic interactions. The remaining phosphine group was subsequently coordinated to Wilkinson's catalyst via ligand exchange. All solids have been characterized by quantitative 31P solid-state NMR spectroscopy. The catalysts, immobilized via the tetraphosphine linker scaffolds with biphenyl spacers, showed high activities and selectivities with respect to the hydrogenation of 1-dodecene. They have been recycled 9 times in a batchwise manner. All immobilized catalysts eventually formed rhodium nanoparticles that retained their catalytic activity even after being exposed to air.

Comparison of macrocyclic and acyclic chelators for gallium-68 radiolabelling.

Gallium-68 (68Ga) is a positron-emitting isotope used for clinical PET imaging of peptide receptor expression. 68Ga radiopharmaceuticals used in molecular PET imaging consist of disease-targeting biomolecules tethered to chelators that complex 68Ga3+. Ideally, the chelator will rapidly, quantitatively and stably coordinate 68Ga3+ at room temperature, near neutral pH and low chelator concentration, allowing for simple routine radiopharmaceutical formulation. Identification of chelators that fulfil these requirements will facilitate development of kit-based 68Ga radiopharmaceuticals. Herein the reaction of a range of widely used macrocyclic and acyclic chelators with 68Ga3+ is reported. Radiochemical yields have been measured under conditions of varying chelator concentrations, pH (3.5 and 6.5) and temperature (25 and 90 °C). These chelators are: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA), 1,4,7-triazacyclononane macrocycles substituted with phosphonic (NOTP) and phosphinic (TRAP) groups at the amine, bis(2-hydroxybenzyl)ethylenediaminediacetic acid (HBED), a tris(hydroxypyridinone) containing three 1,6-dimethyl-3-hydroxypyridin-4-one groups (THP) and the hexadentate tris(hydroxamate) siderophore desferrioxamine-B (DFO). Competition studies have also been undertaken to assess relative complexation efficiencies of each chelator for 68Ga3+ under different pH and temperature conditions. Performing radiolabelling reactions at pH 6.5, 25 °C and 5-50 μM chelator concentration resulted in near quantitative radiochemical yields for all chelators, except DOTA. Radiochemical yields either decreased or were not substantially improved when the reactions were undertaken at lower pH or at higher temperature, except in the case of DOTA. THP and DFO were the most effective 68Ga3+ chelators at near-neutral pH and 25 °C, rapidly providing near-quantitative radiochemical yields at very low chelator concentrations. NOTP and HBED were only slightly less effective under these conditions. In competition studies with all other chelators, THP demonstrated highest reactivity for 68Ga3+ complexation under all conditions. These data point to THP possessing ideal properties for rapid, one-step kit-based syntheses of 68Ga-biomolecules for molecular PET imaging. LC-MS and 1H, 13C{1H} and 71Ga NMR studies of HBED complexes of Ga3+ showed that under the analytical conditions employed in this study, multiple HBED-bound Ga complexes exist. X-ray diffraction data indicated that crystals isolated from these solutions contained octahedral [Ga(HBED)(H2O)], with HBED coordinated in a pentadentate N2O3 mode, with only one phenolic group coordinated to Ga3+, and the remaining coordination site occupied by a water molecule.

Synthetic Models for Nickel-Iron Hydrogenase Featuring Redox-Active Ligands.

The nickel-iron hydrogenase enzymes efficiently and reversibly interconvert protons, electrons, and dihydrogen. These redox proteins feature iron-sulfur clusters that relay electrons to and from their active sites. Reported here are synthetic models for nickel-iron hydrogenase featuring redox-active auxiliaries that mimic the iron-sulfur cofactors. The complexes prepared are NiII(μ-H)FeIIFeII species of formula [(diphosphine)Ni(dithiolate)(μ-H)Fe(CO)2(ferrocenylphosphine)]+ or NiIIFeIFeII complexes [(diphosphine)Ni(dithiolate)Fe(CO)2(ferrocenylphosphine)]+ (diphosphine = Ph2P(CH2)2PPh2 or Cy2P(CH2)2PCy2; dithiolate = -S(CH2)3S-; ferrocenylphosphine = diphenylphosphinoferrocene, diphenylphosphinomethyl(nonamethylferrocene) or 1,1'-bis(diphenylphosphino)ferrocene). The hydride species is a catalyst for hydrogen evolution, while the latter hydride-free complexes can exist in four redox states - a feature made possible by the incorporation of the ferrocenyl groups. Mixed-valent complexes of 1,1'-bis(diphenylphosphino)ferrocene have one of the phosphine groups unbound, with these species representing advanced structural models with both a redox-active moiety (the ferrocene group) and a potential proton relay (the free phosphine) proximal to a nickel-iron dithiolate.

Amino and Alkyl B-Substituted P-Stabilized Borenium Salts

The ability of the phosphino-naphthyl moiety to stabilize amino- and alkylborenium cations has been studied. Surprisingly, the phosphine–aminochloroborane precursor 2 was found to exist in neutral open form (without P→B interaction) in benzene solution and in the solid state but to ionize spontaneously in chloroform to generate the P-stabilized borenium salt 3. Addition of gallium trichloride shifts the process forward and affords the corresponding tetrachlorogallate borenium salt 3′. The phosphine group of 2 remains available for external reactivity, as shown by the ready formation of the corresponding phosphine gold(I) chloride complex 4. The P-stabilized cyclohexylborenium cation 6 has also been prepared by reacting the corresponding bromoborane 5 with gallium tribromide. Compound 6 is a very rare example of an alkyl-substituted borenium salt. The structures of 2, 3′, and 4–6 have been unambiguously ascertained by multinuclear NMR spectroscopy and X-ray crystallography.

Synthesis and metal complexation of a functional fullerene containing amine, phosphine, and pyridine coordinate groups

Treating C60 with o-(diphenylphosphino)benzaldehyde and o-aminomethylpyridine in refluxing o-dichlorobenzene affords a new fullerene derivative syn-PPh2(o-C6H4)(o-C5H4N)(C2H3NC60) (1) in moderate yield. Compound 1 displays versatile coordination modes. Such that, reactions of 1 with Os3(CO)11(NCMe), W(CO)4(NCMe)2, and Ru3(CO)12 produce Os3(CO)11(η1-PPh2(o-C6H4)(o-C5H4N)(C2H3NC60)) (2), W(CO)4(η2-PPh2(o-C6H4)(o-C5H4N)(C2H3NC60)) (3), and Ru(CO)3(η3-PPh2(o-C6H4)(o-C5H4N)(C2H3NC60)) (4), respectively. Interestingly, heating 4 with Ru3(CO)12 leads to transfer of the fullerene addend to give C60 and a tetraruthenium cluster complex (μ-H)Ru4(CO)11(μ4,η4-PPh2(o-C6H4)CH2NC(o-C5H4N)) (5). The structures of 1 and 5 have been determined by an X-ray diffraction study.

Organocatalytic Alkyne Isomerizations under Flow Conditions Using Heterogeneous Bifunctional Polystyrene Bearing Phosphine and Phenol Groups

A heterogeneous bifunctional polymer bearing phosphine and phenol groups was developed to catalyze the isomerization of electronically activated alkynes. This organocatalytic process provided the corresponding (<i>E</i>,<i>E</i>)-dienes and was shown to work under both batch and flow conditions.