Triphenylphosphine Complexes Research Articles

Hydroesterification of tert-butyl alcohol in room temperature ionic liquids

Hydroesterification of tert-butyl alcohol with ethanol catalyzed by transition metal triphenylphosphine complexes in the presence of p-toluenesulfonic acid was investigated using room temperature ionic liquids as the reaction medium at 373–413 K and 3–6 MPa of CO. In comparison with the organic solvents as reaction medium, higher conversion was achieved and ethyl tert-valerate could be directly formed in the ionic liquid medium. The products could be separated from the ionic liquids easily due to their immiscibility in this medium.

Benchmark compounds. Structures of cobalt(II) complexes of triphenylphosphine- and triphenylarsine oxides

The structures of the Co(OPPh3)2Cl2, Co(OPPh3)2Br2, Co(OPPh3)2I2, Co(OAsPh3)2Br2 and Co(OAsPh3)2(NO3)2 complexes have been determined by X-ray diffraction methods; all have pseudo-tetrahedral co-ordination for cobalt.

ChemInform Abstract: Synthesis of Biaryls via Cross‐Coupling Reaction of Arylboronic Acids with Aryl Chlorides Catalyzed by NiCl2/Triphenylphosphine Complexes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Carbenerhodium(I) complexes of the half-sandwich-type: reactions with electrophiles

The reaction of the carbenerhodium(I) complexes [(η5-C5H5)Rh(CR2)(L)] (R = aryl) with HX (X = Cl, CF3CO2) led, depending on the size and donor properties of the ligand L, to two different types of products. While compounds 1, 2 with R = Ph and L = CO or PMe3 react with HX to give rhodium(III) alkyls [(η5-C5H5)RhX(CHPh2)(L)] 3, 4a,b, the analogues 5a and 5b with R = Ph, p-Tol and L = PPri3 afford upon treatment with HX (X = Cl, Br, I, CF3CO2) the ring-substituted products [{η5-C5H4(CHR2)}RhHX(PPri3)] 6a–e. In the presence of excess HX, the latter are converted into the dihalo or bis(trifluoroacetato) derivatives [{η5-C5H4(CHR2)}RhX2(PPri3)] 7a–e. A labelling experiment using [(η5-C5D5)Rh(CPh2)(PPri3)] 5a-d5 as a precursor indicates that the migratory insertion of the carbene into a C–H bond of the cyclopentadienyl ring probably occurs via an η4-cyclopentadienerhodium(I) species as an intermediate. The triphenylphosphine complex [{η5-C5H4(CHPh2)}RhCl2(PPh3)] 7f was prepared analogously from 5c and two equiv. of HCl. The reactions of 5a and 5d (R = Ph, L = SbPri3) with either HBF4, [Me3O]BF4 or methyl triflate give via attack of the electrophile on the carbene carbon atom and subsequent σ/π rearrangement cationic η3-benzylrhodium(III) complexes 9 and 10a–c in good to excellent yields. Treatment of 5a and 5d with iodine results in the cleavage of the metal–carbene bond and affords the diiodo compounds [(η5-C5H5)RhI2(L)] 12a,b.

Excimer Formation in Oligo[2,5-bis(hexadecyloxy)-1,4-phenylene]s Followed by Fluorescence Spectroscopy

Using the steady-state and time-resolved fluorescence spectroscopy, the behavior of "hairy-rod" oligo- and poly[2,5-bis(hexadecyloxy)-1,4-phenylene]s in tetrahydrofuran solutions was investigated. The materials were prepared by the Yamamoto coupling reaction using zinc as a reducing metal, the nickel(II)/triphenylphosphine complex as a catalyst, and 2,2'-bipyridine as a coligand. The appropriate oligomer fractions were separated by fractional precipitation and characterized by GPC and end group analysis. The fluorescence quantum yield of oligomers and polymers increased with their increasing conjugation length. The fluorescence emission spectra of polymers and longer oligomers exhibited one emission maximum at 390 nm with a single-exponential decay and fluorescence lifetimes (τ) around 1 ns. The substitution in positions 2 and 5 forces the adjacent backbone benzene units out of the plane, which results in twist angles 60-80°, and the bulky substituents exclude the cofacial sandwich-type configuration necessary for excimer formation. However, with shorter oligomers, another emission band at 460 nm appeared. Fluorescence decays at 460 nm were found to be double-exponential with longer excited-state lifetimes [e.g. τ1 = 6.9 ns (76%), τ2 = 2.4 ns (24%)]. With shorter oligomers (dimer, trimer), we assume a sandwich-type configuration with sufficiently close interchain distance and hence the excimer can form. Hydrophobic interactions of long aliphatic side chains in a polar medium play an important role in the excimer formation.

Structure of Complexes and Catalytic Oxidation of Triarylphosphine in the Reaction of 9-Phenyl-9-phosphafluorene with Bis(acetylacetonato)palladium

Complex formation of 9-phenyl-9-phosphafluorene with bis(acetylacetonato)palladium in benzene and acetonitrile was studied by means of NMR, IR, and UV spectroscopy. The structure of the resulting complexes, as well as specific features of catalytic oxidation of the arylphosphine and the reduction of Pd(II) to Pd(0) to form the complex Pd(PC1 8H1 3)4 were explored. 9-Phenyl-9-phosphafluorene gives two types of complexes with Pd(acac)2). The first ones are similar to triphenylphosphine complexes, and the others (π complexes) are formed by coordination of the planar aromatic π system of the phosphine to the plane of Pd(acac)2.

Synthesis and characterisation of four-membered ring platinalactam complexes derived from 2-cyanoacetylurea; crystal structure of [ [formula omitted]H(CN)}(PPh 3) 2

The reactions of cis-[PtCl 2L 2] [L=PPh 3 or L 2=dppe (Ph 2PCH 2CH 2PPh 2)] with cyanoacetylurea [NCCH 2C(O)NHC(O)NH 2] and triethylamine gives the platinalactam complexes [ Pt{N(CONH 2)C(O)C H(CN)}L 2]. A single-crystal X-ray diffraction study on the triphenylphosphine complex confirms the presence of the four-membered platinalactam ring; the urea substituent is involved in intra- and intermolecular hydrogen bonding, forming a dimer in the solid state.

Homogeneous hydrogenation of ketones in the presence of H 2 Ru(CO) 2 (PPh 3 ) 2

The hydrogenation of ketones to alcohols in the presence of a hydrido ruthenium triphenylphosphine complex, H 2 Ru(CO) 2 (PPh 3 ) 2 , has been investigated. Acetophenone was hydrogenated at 120 °C with a conversion of 69% after 24 h. The yield is 85% working at 140°C. A kinetic investigation of the reaction was also performed: the reaction is first order with respect to the hydrogen pressure, substrate and catalyst concentration. The rate of hydrogenation depends on the nature of the substrate: steric and electronic effects have a strong influence on the hydrogenation of ketones. 2,2,2-Trifluoroacetophenone is almost completely hydrogenated at 120 °C after 3 h. A mechanism has been tentatively suggested for the hydrogenation of ketones in which the coordination of the substrate to the metal is followed by its insertion into the ruthenium-hydrido bond with formation of the corresponding alkoxide. This complex reacts with hydrogen, restoring the catalyst and forming the alcohol, We have also tested the activity of this catalyst in the hydrogenation of an α,β-unsaturated ketone (trans-4-phenylbut-3-en-2-one). The C=C double bond is preferentially hydrogenated with a high chemoselectivity (92.4% at 100°C). The data collected on the hydrogenation of trans-4-phenylbut-3-en-2-one suggest a different mechanism in which the rate-determining step is the interaction between the C=C double bond of the ketone with the metal-hydrido bond. Experimental evidence is reported to support this different hypothesis.

Reactions of cis and trans Bcat, Aryl Osmium Complexes (cat = 1,2-O2C6H4). Bis(Bcat) Complexes of Osmium and Ruthenium and a Structural Comparison of cis and trans Isomers of Os(Bcat)I(CO)2(PPh3)2

Reaction of Os(Bcat)Cl(CO)(PPh3)2 (1) (HBcat = catecholborane or 1,3,2-benzodioxaborole) with o-tolyllithium gives the yellow, five-coordinate Bcat, aryl complex Os(Bcat)(o-tolyl)(CO)(PPh3)2 (2). Treatment of 2 with carbon monoxide or p-tolylisocyanide gives the corresponding saturated Bcat, aryl complexes cis-Os(Bcat)(o-tolyl)(CO)2(PPh3)2 (3) and cis-Os(Bcat)(o-tolyl)(CO)(CN-p-tolyl)(PPh3)2 (4). Complexes 3 and 4 decompose in benzene solution at room temperature to give o-tolylBcat and the orthometalated triphenylphosphine complexes (5) and (as a mixture of two isomers, 6a and 6b), respectively. In the presence of B2cat2, 3 and 4 react to give the bis(Bcat) complexes Os(Bcat)2(CO)2(PPh3)2 (7) and Os(Bcat)2(CO)(CN-p-tolyl)(PPh3)2 (8). Complex 3 also reacts with HBcat to produce Os(Bcat)H(CO)2(PPh3)2 (9). The bis(Bcat) ruthenium complexes Ru(Bcat)2(CO)2(PPh3)2 (10) and Ru(Bcat)2(CO)(CN-p-tolyl)(PPh3)2 (11) can be prepared by treatment of Ru(CO)2(PPh3)3 or Ru(CO)(CN-p-tolyl)(PPh3)3 with B2cat2. Complex 3 reacts with Cl2CCCl2 or CHCl3 to produce OsCl(CClCCl2)(CO)2(PPh3)2 (12) or OsCl2(CO)2(PPh3)2, respectively. Complex 1 when treated with CO gives cis-Os(Bcat)Cl(CO)2(PPh3)2 (13), which in turn with phenyllithium or o-tolyllithium gives trans-Os(Bcat)(Ph)(CO)2(PPh3)2 (14) or trans-Os(Bcat)(o-tolyl)(CO)2(PPh3)2 (15). Complex 15 reacts with I2 to give a mixture of trans-Os(Bcat)I(CO)2(PPh3)2 (16) and trans-Os(o-tolyl)I(CO)2(PPh3)2 (17). Complex 16 is also formed by heating cis-Os(Bcat)I(CO)2(PPh3)2 (18) in benzene. Crystal structures of complexes, 5, 8, 10, 11, 12, 16, and 18 are reported.

Synthesis and Structural Characterization of Silver(I) and Gold(I) Complexes with 2-Mercaptonicotinic Acid (H2mna) and Triphenylphosphine Ligands, and Their Antimicrobial Activities. Crystal Structures of Monomeric, 3- and 4-Coordinate Silver(I) Complexes [Ag(Hmna)(PPh3)2] and [Ag(Hmna)(PPh3)3] in the Solid State

Abstract Two types of silver(I)-triphenylphosphine complexes with 2-mercaptonicotinic acid (H2mna) were prepared as [Ag(Hmna)(PPh3)n] (1, n = 2; 2, n = 3); their crystal structures determined by single-crystal X-ray diffraction. These complexes were obtained from reactions of the precursor, [Ag(Hmna)]n, with less excess (3 equiv) and large excess (20 equiv) amounts of PPh3, respectively. Complex 1 was also obtained from a reaction among another precursor [AgCl(PPh3)3], H2mna and aqueous NaOH. The coordination geometry of 1 was a trigonal pyramid with an AgSP2 core; there was a weak interaction between the silver(I) center and the pyridine nitrogen atom, while that of 2 was a distorted tetrahedron with an AgSP3 core. In both 1 and 2, the carboxyl group was protonated and its oxygen atoms did not participate in the coordination. In contrast to the formation of 1 and 2, a related complex, [Ag(Hmba)(PPh3)3] 4 (H2mba = 2–mercaptobenzoic acid), has been obtained from a reaction of [Ag(Hmba)]n with a stoichiometric amount (3 equiv) of PPh3. On the other hand, the gold(I) complex, [Au(Hmna)(PPh3)] 3, with a 2-coordinate AuSP core, was prepared by a stoichiometric reaction among [AuCl(PPh3)], H2mna and aqueous NaOH. Complex 3 in the solid state showed a supramolecular array based on a repetition of hydrogen-bonding interactions between the carboxyl group and the pyridine nitrogen atom, also being contrasted to the related complex, [Au(Hmba)(PPh3)] 5, with a hydrogen-bonding dimer structure in the solid state. In CHCl3, both 1 and 2 were present as several equilibrium species due to a successive dissociation of PPh3 ligands, while 3 was present as an almost monomer. The antimicrobial activities in aqueous media of 1—5, evaluated by minimum inhibitory concentration (MIC), were also tested.

B-stage characterization of o-cresol novolac epoxy resin system using raman spectroscopy and matrix-assisted laser desorption/ionization mass spectrometry

The B-stage of the o-cresol novolac epoxy resin–phenol novolac hardener–triphenylphosphine (TPP) catalyst system was characterized using Raman spectroscopy and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The consistent decreasing intensities of characteristic epoxy resin peaks in MALDI mass and Raman spectra according to the melt mixing time were observed, which is due to the formation of the epoxy–phenol–TPP complex and the propagation reaction between them and with another epoxy resin. Our microscopic analysis method will provide a useful tool to control the optimum condition of the melt mixing process in the B-stage. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1940–1946, 2000

Synthesis, crystal structure and antimicrobial activities of two isomeric gold(I) complexes with nitrogen-containing heterocycle and triphenylphosphine ligands, [Au(L)(PPh 3)] (HL=pyrazole and imidazole)

Two isomeric gold(I)–triphenylphosphine complexes with nitrogen-containing heterocycles, [Au(L)(PPh 3)] (HL=pyrazole ( 1), imidazole ( 2)), were isolated as colorless cubic crystals for 1 and colorless plate crystals for 2, respectively. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction. These complexes were also fully characterized by complete elemental analyses, thermogravimetric/differential thermal analyses (TG/DTA) and FT-IR in the solid state and by solution NMR ( 31P, 1H and 13C) spectroscopy and molecular weight measurements in acetone solution. These complexes consisted of a monomeric 2-coordinate AuNP core both in the solid state and in solution. The molecular structures of 1 and 2 were compared with those of related gold(I) complexes, [Au(1,2,3-triz)(PPh 3)] ( 3, Htriz=triazole), [Au(1,2,4-triz)(PPh 3)] 2 ( 4) as a dimer through a gold(I)–gold(I) bond in the solid state, and [Au(tetz)(PPh 3)] ( 5, Htetz=tetrazole). Selective and effective antimicrobial activities against two Gram-positive bacteria ( B. subtilis, S. aureus) and modest activities against one yeast ( C. albicans) found in these gold(I) complexes 1– 4 are noteworthy, in contrast to poor activities observed in the corresponding silver(I) complexes.

Synthesis and crystal structure of coinage metal(I) complexes with tetrazole (Htetz) and triphenylphosphine ligands, and their antimicrobial activities. A helical polymer of silver(I) complex [Ag(tetz)(PPh 3) 2] n and a monomeric gold(I) complex [Au(tetz)(PPh 3)

Two novel coinage metal(I)-triphenylphosphine complexes with a heterocyclic ligand, [Ag(tetz)(PPh 3) 2] n ( 1) and [Au(tetz)(PPh 3)] ( 2) (Htetz=tetrazole) were synthesized from a reaction in dichloromethane of the precursor complex [Ag(tetz)] n with PPh 3 and from a reaction in acetone of [AuCl(PPh 3)] with Htetz in the presence of aqueous NaOH, respectively, and isolated as colorless needle crystals for both 1 and 2. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction. These d 10 complexes were also fully characterized by elemental analyses, TG/DTA and FT-IR in the solid-state, solution NMR ( 31P, 1H and 13C, as well as 109Ag for 1) spectroscopies and solution molecular weight measurements. Complex 1, is composed of a helical polymer, a 2 1 helix with a pitch 9.471 Å, formed by a bridged tetrazolate of an AgNP 2 core in the solid-state, but it was present as a monomer in solution. In contrast to 1, complex 2 consisted of a monomeric two-coordinate AuNP core without gold(I)–gold(I) interaction both in the solid-state and in solution. The molecular structures of 1 and 2 were compared with those of the corresponding triazole complexes, i.e. silver(I) complexes [Ag(1,2,3-triz)(PPh 3) 2] n ( 3) and [Ag(1,2,4-triz)(PPh 3) 2] n ( 4) both as helical polymers, a monomeric gold(I) complex [Au(1,2,3-triz)(PPh 3)] ( 5) and a dimeric gold(I) complex [Au(1,2,4-triz)(PPh 3)] 2 ( 6) through an intramolecular gold(I)–gold(I) bond; the structures of complexes 3– 6 being recently determined by X-ray crystallography. The antimicrobial activities of 1, its precursor [Ag(tetz)] n and 2 were compared and key factors affecting them discussed.

Evidence for the hydride mechanism in the methoxycarbonylation of ethene catalysed by palladium–triphenylphosphine complexes

Analysis of the phosphorus containing by-products from the catalytic methoxycarbonylation of ethene using a palladium triphenylphosphine complex with a combination of High Performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS) indicated increasing levels of phosphonium salts through the course of the reaction, major ones being methyltriphenylphosphonium, ethyltriphenylphosphonium and 3-oxopentyltriphenylphosphonium (CH3CH2C(O)CH2CH2PPh3) cations, isolated as the sulfonate salts. The latter are shown to be produced by metal mediated pathways and believed to be indicative of the operation of the hydride mechanism.

High-Spin Polyphenoxyl Based on Poly(1,4-phenyleneethynylene)

Rodlike poly(1,4-phenyleneethynylene) 2-substituted with multiple pendant phenoxyls 1 was synthesized by polymerizing 4-bromo-2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethynylbenzene 10a using the catalyst of a palladium−triphenylphosphine complex and cuprous iodide and subsequent heterogeneous oxidation. The corresponding dimer 2 was also synthesized; X-ray analysis of its precursor 4 indicated a linear phenyleneethynylene backbone and twisted dihedral angles of 50 and 77° for the pendant phenol groups. ESR spectra suggested a delocalized spin distribution from the pendant phenoxyl to the backbone. The diphenoxyl 2 had a triplet (S = 2/2) ground state. The spin concentration of the polyphenoxyl 1 could not be increased beyond 0.7 spin/unit due to its low solvent solubility; 1 with a spin concentration of 0.62 had an average S of 3/2.

Crystal Engineering of Gold(I) Thiolate Based Compounds via Cooperative Aurophilic and Hydrogen-Bonding Interactions

Treatment of sodium 2-amino-5-mercapto-1,3,4-thiadiazolate (NaSSNH2) with monophosphines (triphenylphosphine and trimethylphosphine) and diphosphines [bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), and trans-1,2-bis(diphenylphosphino)ethene (dppee)] affords a series of gold(I) thiolates with the respective stabilizing phosphine ligands [Au(PR3)(SSNH2)] (R = Ph 1 and Me 2) and [PP(Au(SSNH2))2] (PP = dppm 3, dppe 4 and dppee 5). The crystal structures of the complexes have been determined by single-crystal X-ray diffraction studies, confirming hydrogen-bonded frameworks in the crystal lattices based on the functions of the SSNH2 ligands. The triphenylphosphine complex 1 (with crystal diethyl ether, 1·0.5Et2O) forms a dimer solely via bifurcated hydrogen bonds. In the presence of crystal methanol (1·MeOH) it gives rise to a one-dimensional ladder structure via intermolecular hydrogen-bonding interactions with molecules of crystal methanol as bridges. With a reduced steric effect of the auxiliary ligand, the trimethylphosphine analogue 2 forms a novel two-dimensional sheet structure via cooperative intermolecular aurophilic [Au(I)···Au(I) 3.0581(6) Å] and hydrogen-bonding interactions. The bis(diphenylphosphino)methane complex 3·2DMF features dinuclear units associated into a meandering chain structure via intramolecular aurophilic and intermolecular hydrogen bonding interactions. Further aggregation is terminated by hydrogen-bonding to crystal solvent molecules. 4·0.5MeOH forms a complicated network via cooperative intermolecular aurophilic [Au(I)···Au(I) 3.0675(7) Å] and hydrogen-bonding interactions. With DMF as a chain-terminating solvent molecule, the trans-1,2-bis(diphenylphosphino)ethylene complex 5·4DMF can only form isolated dinuclear units hydrogen bonded to these solvent molecules. Complexes 2 and 4 are rare examples of two-dimensional frameworks built on cooperative intermolecular aurophilic and hydrogen-bonding interactions in the solid state.

ChemInform Abstract: Halogenation of Carbohydrates by Triphenylphosphine Complex Reagents in Highly Concentrated Solution under Microwave Activation or Conventional Heating.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Hydrogenation reactions on heterogenized Wilkinson complexes

A novel clay catalyst containing a heterogenized Rh(I) triphenylphosphine complex (Rh-bentonite) has been prepared via ion exchange of a Hungarian Na +-bentonite with Wilkinson complex [RhCl(PPh 3) 3]. It was established that the active species [Rh(PPh 3)] + was situated on the external surface of the catalyst, which was found to be efficient in the liquid-phase hydrogenation of 1-octene, cyclohexene, norbornadiene, 1,5-cyclooctadiene, phenylacetylene and cyclohexene-3-one.

Halogenation of carbohydrates by triphenylphosphine complex reagents in highly concentrated solution under microwave activation or conventional heating

Halogenation of carbohydrates with triphenylphosphine and carbon tetrachloride, hexachloroethane or 1,2-dibromotetrachloroethane was shown to be very efficient in highly concentrated solutions of nonpolar solvents such as toluene or 1,2-dichloroethane, with, in some cases, addition of potassium chloride, potassium bromide, and/or pyridine. The reactions were very fast under microwave irradiation (2 to 30 min) as well as by classical heating (2 to 45 min) at 80–120 °C. Most often, the yields were better under microwave irradiation and the reaction product distribution was sometimes different from that obtained with classical methods with, in all experiments, the amount of solvent strongly reduced.

31P chemical shift anisotropies of trimethyl- and triphenylphosphine-substituted Group 6 metal pentacarbonyl complexes

The 31P chemical shift tensor components and anisotropies of the trimethyl- and triphenylphosphine complexes of the group 6 metal pentacarbonyls, M(CO)5PR3 (M = Cr, Mo, W and R = Me, Ph), have been measured using solid-state CP-MAS 31P NMR spectroscopy. For the trimethylphosphine derivatives, the chemical shift tensors have near axial symmetry and the shift tensor components are in reasonable agreement with the calculated values for the chromium and molybdenum complexes. In the triphenylphosphine complexes, the tensors are asymmetric due to the different torsion angles of the phenyl rings. The trend to higher shielding of the isotropic 31P chemical shifts on descending group 6 arises from changes in the perpendicular components of the shift tensor. The one-bond coupling constants, 1J(95/97Mo-31P), for the trimethyl- and triphenylphosphine complexes are 129 and 133 Hz, respectively.Key words: chemical shift anisotropy, phosphines, chromium, molybdenum, tungsten.