Addition Of PPh3 Research Articles

New Sustainable Pd(II)/Fe(III) Catalytic System Very Efficient in the Hydromethoxycarbonylation of 1-octene

In order to increase the catalytic activity of the Pd(II)-complexes in the alcoxycarbonylation of 1-olefins, the presence in solution of a strong Brönsted acid together with a phosphine ligand is usually required. From an industrial point of view, such two additives, however, influenced the sustainability of the process mainly caused by the related corrosion of the reaction vessel and the toxicity of the phosphine ligand.In this paper, the methoxycarbonylation of 1-octene has been efficiently carried out by using the [Pd(TsO)2(PPh3)2]/FeCl3 catalyst system. The catalyst is very active also without addition of PPh3, reaching the TON of ca. 1300 (mol/mol) in 2 hours by using the Fe(III)/Pd(II) = 400/1 (mol/mol) system. Such value is higher than the values obtained by using the traditional strong Brönsted acid TsOH or other Lewis acid such as AlCl3, in the presence of PPh3. The reaction takes place with the formation of two isomeric products of linear and branched structures with a yield towards the linear isomer of ca. 80%.

Intelligent Colorimetric Sensor for Discriminative Detection of Pd2+/Pd0 and PPh3 at Different Wavelength Readouts

AbstractIn this report, we presented our results on a recognition of multiple analytes using trisubstituted PDI‐based chemosensor DNP in 50 % HEPES buffered‐CH3CN solution. Upon addition of Pd2+ or Pd0, DNP showed near IR ratiometric changes (A759nm/A560nm) with detection limit of 283 nM and 190 nM, respectively. These spectroscopic changes are associated with color change from violet to light yellow (de‐propargylation). The de‐propargylation reaction of DNP is faster in the presence of Pd2+ than Pd0. Upon addition of PPh3, DNP resulted in appearance of new bands at 615 and 698 nm with decrease of absorbance intensity at 560 nm with detection limit of 349 nM. Two isosbestic points at 504 nm and 600 nm was observed. This change is associated with color changes from violet to blue. DNP coated TLC‐strips can be used for the detection of 4×10−4 M Pd0 and PPh3. We have demonstrated the practical application of DNP (i) for the detection of Pd0 in live A549 cells and (ii) for detection of Pd2+/Pd0 in simulated urine (10 %) samples with recovery of (>98±5 %).

Beneficial Effect of a Secondary Ligand on the Catalytic Difunctionalization of Vinyl Arenes with Boron and CO2

AbstractThe boracarboxylation of vinyl arenes catalyzed by copper(I) is an alkene difunctionalization reaction that provides synthetically useful β‐boryl‐α‐aryl propanoic acid derivatives. Drawbacks of the original reaction methodology are high catalyst loading and vinyl arene scope limited largely to electron‐rich systems. Herein, we demonstrate that catalytic additives, specifically triphenylphosphine or electron‐rich styrene, leads to improved catalyst efficiency and broadening of substrate scope. With the addition of PPh3, comparable yields of previously reported boracarboxylated substrates as well as two novel β‐boronated non‐steroidal anti‐inflammatory drugs (bora‐fenoprofen and bora‐flurbiprofen) were achieved at lower catalyst loading. Boracarboxylation of electron‐deficient substrates could be achieved through superstoichiometric addition of vinyl arene or addition of secondary phosphine ligand. Reactivity optimization and competition experiments have provided preliminary insights into the ability of PPh3 to aid in the catalytic cycle, specifically carboxylation of electron‐rich benzyl‐copper(I) intermediate. Additional competition studies revealed that a catalytic amount of an electron‐rich vinyl arene could be used in addition to the copper(I) catalyst to promote boracarboxylation of an electron‐deficient styrene derivative.

Synthesis of stereoblock polybutadiene possessing cis-1,4 and syndiotactic-1,2 segments by imino-pyridine cobalt complex-based catalyst through one-pot polymerization process

The iminopyridylcobalt complexes Co1-Co5 bearing bulky phenethyl or benzhydryl substituents were synthesized. Determined by single crystal X-ray crystallographic analysis, complexes Co3 and Co4 displayed tetrahedron geometries. The present complexes displayed high cis-1,4 selectivity for 1,3-butadiene polymerization upon activation with ethylaluminum sesquichloride (EASC). While upon activation with either methylaluminoxane (MAO) or trialkylaluminum-free MAO (dMAO) cocatalyst, these complexes exhibited moderate activities, addition of PPh3 into the catalyst system resulted in the increase in catalytic activities and the change of the selectivity from cis-1,4 to 1,2 manner. Moreover, the livingness of Co4/dMAO system enabled synthesis of cis-1,4-b-syn-1,2 stereodiblock polybutadiene with PPh3 as a selectivity regulating agent in one-pot polymerization process. Crystallization of syn-1,2 block and attendant expulsion of cis-1,4 block from the crystalline structure led to micro-phase separation in this stereoblock polymer.

Gold(I), Phosphanes, and Alkynyls: The Perfect Allies in the Search for Luminescent Compounds

A family of mixed phosphane/alkynyl gold(I) complexes was prepared by addition of PPh3 or PPh2py to suspensions of the polymeric species [Au(C≡CR)n] [R = Ph, 2‐pyridyl (py)] and [Au2{C≡C(CH2)3C≡C}]n. The resulting complexes are luminescent both at room and low temperature, in solution and in the solid state. The emissions are assigned to intraligand transitions associated with the C≡C moieties or related to 3[σ(Au–P)→π*(C≡Cpy)] transitions. The crystal structure of dinuclear complex [Au2{C≡C(CH2)3C≡C}(PPh2py)2] shows the presence of dimers stabilized by intermolecular aurophilic interactions.

An N-Heterocyclic Carbene-Nickel Half-Sandwich Complex as a Precatalyst for Suzuki-Miyaura Coupling of Aryl/Heteroaryl Halides with Aryl/Heteroarylboronic Acids.

A nickel half-sandwich complex supported by our original NHC ligand was developed as a robust precatalyst for Suzuki-Miyaura cross-coupling. The addition of PPh3 was a crucial element in the suppression of side reactions and in accelerating the cross-coupling reaction. By employing the optimal conditions, aryl-aryl, heteroaryl-aryl, and heteroaryl-heteroaryl couplings were achieved.

Pyridine–oxazoline and quinoline–oxazoline ligated cobalt complexes: Synthesis, characterization, and 1,3-butadiene polymerization behaviors

A series of cobalt complexes supported by pyridine–oxazoline (Pyox) and quinoline–oxazoline (Quox) were synthesized. Determined by single crystal X-ray crystallography, complexes 6a and 7c adopted distorted octahedron and trigonal bipyramid geometries, respectively, while complex 6b existed as an ion pair comprised of [CoL2]2+ and [CoCl4]2−, in which the cationic and anionic moieties displayed distorted octahedron and tetrahedral geometries, respectively. Upon activation with ethylaluminium sesquichloride (EASC), these cobalt complexes exhibited high catalytic activity and cis-1,4-selectivity toward 1,3-butadiene polymerization. The selectivity of the catalytic system could be switched from cis-1,4 to 1,2-fashion via the addition of PPh3. The effects of ligand environment, polymerization temperature, and [Al]/[Co] ratio on the polymerization were investigated in detail.

Synthesis, characterization and 1,3-butadiene polymerization studies of cobalt dichloride complexes bearing pyridine bisoxazoline ligands

A series of ion-pair cobalt complexes bearing pyridine bisoxazoline ligands were successfully synthesized and characterized by IR spectroscopy and elemental analysis. Determined by X-ray crystallographic analysis, complexes 4a, 4b, 4e, and 4f existed as ion pairs comprised of [CoL2]2+ and [CoCl4]2−. In the complex, the cobalt atom was coordinated by six nitrogen atoms from two ligands, and its coordination geometry at the cobalt center of [CoL2]2+ can be described as distorted octahedron. In combination with ethylaluminum sesquichloride, these cobalt complexes displayed high catalytic activity and cis-1,4-selectivity towards 1,3-butadiene polymerization. The selectivity of the catalytic system can be tuned to predominantly 1,2-fashion via addition of PPh3. The effects of reaction parameters and the ligand environment on the polymerization were also investigated.

Formation of an Oxidant-Sensible Pd(II) Coordination Compound and Its 1H NMR Specific Characterization: A Preparative and Analytical Challenge in Current Coordination Chemistry

A three-part experiment that leads to the synthesis of palladium(II) complex starting from a C3-symmetric triaminoguanidinium-based ligand is presented. In the first part, the preparation of tris-benzylidenetriaminoguanidinium chloride ([H6Br3L]Cl) by an acidic catalyzed 3-fold imine formation reaction of 5-bromo-2-hydroxybenzaldehyde and triaminoguanidinium chloride is described. Starting from the second part, the reaction procedures are performed under inert gas atmosphere. The conversion of PdCl2 with acetonitrile to give [Pd(MeCN)4]Cl2 as a precursor is performed at 80 °C. The third part of the experiment is a three-step procedure that begins with deprotonation of [H6Br3L]Cl, followed by transfer of [Pd(MeCN)4]Cl2 to the reaction flask, where the chelation of Pd(II)-precursor leads to the in situ species [Pd(MeCN)H3Br3L]. Addition of PPh3 as the final reaction step yields [Pd(PPh3)H3Br3L]. This sequence of experiments provides an excellent example of ligand and transition metal preparation and its subsequent complexation to form an oxidant-sensitive organometallic species. Undergraduate students get the opportunity to learn Schlenk techniques and to investigate 1H NMR spectra of organic and organometallic compounds starting from relatively simple to more advanced spectra. The distinct result of the chemical shift of the 4JP–H-affected doublet mirrors the preparative success of the student and demonstrates the utility of 1H NMR experiments.

Synthesis, characterization and 1,3-butadiene polymerization behaviors of three ONO, ONN, and NNN tridentate Co(II) complexes

Three kinds of ONO (a), ONN (b), and NNN (c) tridentate Co(II) complexes were synthesized and thoroughly characterized. Determined by single crystal X-ray analysis, the solid structures of b and c displayed distorted trigonal bipyramidal and square pyramidal geometries around the metal centre, respectively. In combination with methylaluminoxane (MAO), all three complexes exhibited high catalytic activities towards 1,3-butadiene polymerization, affording polymers with predominant cis-1,4-contents. With addition of PPh3 into the polymerization system, polybutadienes having predominant 1,2-contents were obtained, while the addition of PO(OPh)3 showed little influence on the microstructure of the polymer. In the investigation of chain transfer polymerization of 1,3-butadiene at the presence of ZnEt2, for complexes a and b, monotonous decreasing in molecular weight along with and an increasing of cis-1,4-content were obtained with an increasing molar ratio of Zn/Co, for complex c, however, unconspicuous changes was observed.

Synthesis and application of FeIII, NiII and MnII complexes anchored to HMS as efficient catalysts for cycloalkane oxyfunctionalization

Methoxysilane Schiff-base pentacoordinate metal complexes, i.e. Fe[Sal(PMeO-Si)DPTA], Ni[Sal(PMeO-Si)DPTA] and Mn[Sal(PMeO-Si)DPTA], were synthesized and single site covalently anchored into the uniform porous texture of HMS (2–10nm size) via condensation process. The correspondent supported catalysts (4.a, 4.b and 4.c, respectively) were characterized by FT-IR, SEM/EDS, XRD, TG, EPR and AAS analysis. In the catalytic tests, they showed high efficiency in the selective oxidation of cyclohexane using molecular O2 (overall conversion 40.7% with Cat. 4.a, 29.5% with Cat. 4.b and 26.2% with Cat. 4.c) under relatively mild condition in batch reactor. The Cat. 4.a system (HMS/3.a) exhibits highest TONs ca. 4.2×103 with good selectivity ca. 70% (48% ketone selectivity). The reaction mechanism involves free radicals, as it was proved by the addition of PPh3. Finally, these supported catalysts could be reuse up to several catalytic cycles.

Coinage (Cu, Ag) metal derivatives of salicylaldehyde N-ethylthiosemicarbazone: synthesis, spectroscopy, and structures

Reactions of copper(I) halides with triphenyl phosphine in acetonitrile followed by the addition of salicylaldehyde N-ethylthiosemicarbazone {(2-OH–C6H4)(H)C2=N3–N2H–C1(=S)N1HEt, H2stsc-NEt} in chloroform in 1 : 2 : 1 (Cl) or 1 : 1 : 1 (Br, I) molar ratios yield mononuclear, [CuCl(η 1-S-H2stsc-NHEt)(PPh3)2] (1) and sulfur-bridged dinuclear, [Cu2X2(μ-S-H2stsc-NEt)2(PPh3)2] (X = Br, 4; I, 5) complexes. Similarly, reaction of silver halides (Cl, Br) with H2stsc-NEt in acetonitrile followed by the addition of PPh3 to the solid that formed (1 : 1 : 2 molar ratio), yielding mononuclear complexes, [AgX(η 1-S-H2stsc-NHEt)(PPh3)2] (Cl, 2; Br, 3). All these complexes are characterized with analytical data, IR, and NMR spectroscopy and single-crystal X-ray crystallography. The ligand favored η 1-S bonding in 1, 2, and 3, and μ-S bonding in 4 and 5. Cu ··· Cu contacts were 3.063 Å. The complexes form 1-D or 2-D H-bonded networks, entrapping solvent in some cases.

Crystal structure of K2[Mo3(PdPPh3)S4(C2O4)3(H2O)3]·0.5H2O

By the reaction of [Mo3S4(C2O4)3(H2O)3]2− with PdCl2 and NH4H2PO2 as a reducing agent, followed by the addition of PPh3, a new oxalate cuboidal cluster complex [Mo3(PdPPh3)S4(C2O4)3(H2O)3]2− is obtained. It was isolated and structurally characterized as K2[Mo3(PdPPh3)S4(C2O4)3(H2O)3]·0.5H2O.

Rhodium catalyzed hydroformylation of monoterpenes containing a sterically encumbered trisubstituted endocyclic double bond under mild conditions

The rhodium catalyzed hydroformylation of endocyclic monoterpenes, that is, 2-carene (1), 3-carene (2), and α-pinene (3), in the presence of PPh3 or various diphosphines and phosphites has been studied. The unmodified Rh catalyst promotes an intense isomerization of both carenes whose hydroformylation occurs rather slowly, and results in a complex mixture of aldehydes and alcohols. The addition of PPh3, diphosphines or P(OPh)3 in a P/Rh ratio as high as 20, efficiently prevents the isomerization, but the activity for hydroformylation is drastically reduced. On the other hand, the use of a bulky P(O-o-tBuPh)3 ligand both reduces the isomerization, and significantly increases the hydroformylation rate. All three sterically crowded olefins 1–3 have been efficiently hydroformylated under relatively mild reaction conditions (80–100 °C, 40–80 atm) to a main aldehyde (2-formylcarane, 4-formylcarane, and 3-formylpinene, respectively) with good chemo- and regioselectivity, and almost 100% stereoselectivity for the trans isomers.

Dehalogenation of Hexachlorocyclohexanes and Simultaneous Chlorination of Triethylsilane Catalyzed by Rhodium and Ruthenium Complexes

Complexes RhCl(PPh3)3 and RhH2Cl(PiPr3)2 catalyze the dehalogenation of γ-hexachlorocyclohexane to benzene and the simultaneous chlorination of HSiEt3 to ClSiEt3. In the presence of RhCl(PPh3)3, the dehalogenation is inhibited by addition of PPh3. 1H and 31P{1H} NMR spectroscopy studies at variable temperature, on the behavior of the complex RhCl(PPh3)3 in the presence of γ-hexachlorocyclohexane and/or HSiEt3, indicate that the catalytic reaction involves the initial interaction of the catalyst with the silane and that chloro−hydride intermediates related to RhH2Cl(PPh3)3 are the main species during the catalysis. The complexes RuHCl(PPh3)3, RuH2Cl2(PiPr3)2, and RuHCl(η2-H2)(PiPr3)2 also catalyze the dehalogenation of γ-hexachlorocyclohexane and the simultaneous chlorination of HSiEt3 to ClSiEt3. In these cases, the dehalogenation products are 6/4 cyclohexene/cyclohexane (RuHCl(PPh3)3) and 4/6 cyclohexene/benzene (RuH2Cl2(PiPr3)2 and RuHCl(η2-H2)(PiPr3)2) mixtures. The dehalogenations of α- and δ-hexachlo...

Oxorhenium(V) Complexes Derived from 8,17-Dimethyl-6,15-Dioxo- 5,7,14,16-Tetrahydrodibenzo[a,h][14] Annulene-2,11-Dicarboxylic Acid and their Pyrolytical Products

A new series of oxorhenium(V) complexes were prepared by reaction of 8,17-dimethyl-6,15-dioxo-5,7,14,16-tetrahydrodibenzo[a,h][14] annulene-2,11-dicarboxylic acid(H4L), alone or with addition of PPh3 or NaSCN, with H2[ReOCl5]. Mononuclear complexes, [ReO(H4L)Cl]Cl2, [ReO(H4L)(PPh3)]Cl3, and [ReO(H4L)- (SCN)]Cl2 were obtained in 6 N HCl, while the binuclear complex, [Re2O3(H4L)2]Cl4 was obtained in 2 N HCl. Thermal studies on these complexes showed the possibility of obtaining new complexes pyrolytically, where the complexes decompose through several isolable as well as nonisolable, intermediates during heating. [Re2O3(H2L)2], [ReO(H2L)Cl], [ReO(H2L)(PPh3)]Cl, and [ReO(H2L)(SCN)], were synthesized pyrolytically in the solid state from the respective precursor rhenium complexes. All of the prepared complexes and their thermal products have octahedral configurations. The ligand (H4L) behaves either as a neutral tetradentate or dianionic tetradentate ligand towards the oxorhenium ions in these complexes. The carboxylate groups are not coordinated to oxorhenium ions, which was checked by the acidity test and/or addition of metal ions such as Cu(II) and Ni(II), where a variety of new complexes coordinated via carboxylate groups were obtained. The screening of antibacterial and antifungal activities on the free ligand and all complexes, showed higher antifungal activities against Alternaria alternata than against Aspergillus fumigatus. The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, 1H-NMR and TG-DSC measurements as well as by mass spectrometry.

Reactivity of the Carbyne Complexes [W2(μ-COR)(η5-C5H5)2(CO)2(μ-Ph2PCH2PPh2)]+(R = H, Me) toward Diazomethane

Reaction of [W2(μ-COH)Cp2(CO)2(μ-dppm)]BF4 (Cp = η5-C5H5; dppm = Ph2PCH2PPh2) with CH2N2 in the presence of CuCl at −75 °C leads to the methoxycarbyne cluster [CuW2Cl(μ3-COMe)Cp2(CO)2(μ-dppm)]BF4. Copper(I) chloride can be cleanly removed from the latter upon addition of PPh3, thus giving the methoxycarbyne complex [W2(μ-COMe)Cp2(CO)2(μ-dppm)]BF4. In the absence of CuCl, either the hydroxy or the methoxycarbyne ditungsten cations react with CH2N2 to give a mixture of the μ-methylene, μ-alkenyl compound [W2(μ-CH2){μ-η1:η2-C(OMe)CH2}Cp2(CO)2(μ-dppm)]BF4, which has been characterized through an X-ray study, and the μ-alkyne, μ-alkenyl species [W2{μ-η1:η2-C(OMe)CH}{μ-η1:η2-C(OMe)CH2}Cp2(CO)(μ-dppm)]BF4, the latter being the result of the addition of four molecules of CH2N2 to the starting hydroxycarbyne compound. The influence of experimental conditions on the above reactions has been analyzed through separate experiments. For example, the use of tetrahydrofuran as solvent almost suppresses the formation of t...

Transformations of alkynyl ligands at iron centres: alkenyl formation via addition of PPh3 and enyne generation via head-to-head coupling and addition of benzene

Thermolysis of Fe2(CO)6(µ-PPh2)(µ-C2But) affords the binuclear alkenyl complex Fe2(CO)5(µ-PPh2)(µ-o-Ph2PC6H4CCHBut) and the trinuclear arene complex Fe3(CO)4(µ3-o-PhPC6H4PPh){µ3-C(But)CCHCBut-η6-C6H5} both resulting from a number of novel transformations including C–C bond formation and C–H and C–P bond cleavage and reformation.

Replacement of the chloride ligand in [Au(C,N,N)Cl][PF6] cyclometallated complexes by C, N, O and S donor anionic ligands

Replacement of the chloride ligand in the cyclometallated complexes [Au(C,N,N)Cl][PF6] (C,N,N = N2C10H7(CH2C6H4)-6 1, N2C10H7(CHMeC6H4)-6 2, or N2C10H7(CMe2C6H4)-6 3, where N2C10H8 = 2,2′-bipy) by C, N, O and S donor anionic ligands Y was accomplished through different routes depending both on the nature of HY or the C,N,N ligand. Stable alkoxo [Au(C,N,N)(OR)][PF6] (R = Me or Et) and amido [Au(C,N,N)(NHAr)][PF6] (Ar = C6H4NO2-4) complexes were obtained in fairly good yields. The molecular structure of the thiolato complex [Au{N2C10H7(CMe2C6H4)-6}(SPh)][PF6] has been determined by X-ray crystallography. The diorganogold(III) complex [Au(C,N,N)(C2Ph)][PF6] on addition of PPh3 (1∶2) undergoes reductive elimination to give [Au(PPh3)2][PF6] and an unsymmetric diarylacetylene.

The chemistry of pyridinethiols and related ligands, Part 9. Synthesis, spectroscopy and crystal structure of sulphur bridged dimeric [{η3-(O-μ-S)-1-oxopyridine-2-thione}(triphenylphosp hine)silver(I)

Reaction of 1-hydroxypyridine-2-thione (HpyOS) in CHCl3 with Ag2CO3 suspended in CHCl3 under magnetic stirring followed by addition of PPh3 yields a product of stoichiometry: Ag(pyOS)(PPh3). The compound adopts a dimeric structure [Ag(pyOS)(PPh3)]2 (1) where each Ag atom acquires a distorted tetrahedral geometry by co-ordinating to one oxygen, two sulphur and one phosphorus atoms. The Ag2S2 core forms a parallelogram [Ag—S 2.507(1), 2.822(1)A] with Ag—S—Ag and S—Ag—S angles of 74.8(1) and 105.2(1)°, respectively.