- ELECTROCHEMICAL BEHAVIOUR OF Pd(0) AND Pd(II) COMPLEXES WITH TRIPHENYLPHOSPHINE IN DIMETHYLFORMAMIDE.
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The electrochemical behaviour of a palladium electrode in the presence of ligands such as chloride ions and triphenylphosphine (PPh//3) in dimethylformamide (DMF) solution, and that of a DMF solution of palladium chloride in the presence of the same ligands were investigated by cyclic voltammetry and chronopotentiometric techniques. The PdCl//2-ligands solution systems form a well-defined redox couple at high ( greater than 4) PPh//3 to Cl** minus concentration ratio. The redox couple corresponds to a quasi-reversible surface process, whereas the anodic dissolution of Pd in the presence of ligands is better described as a catalytic reaction with an irreversible charge transfer.
- Vasini, E. J.,Giordano, M. C.
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- Influences of the electronic and steric effects of the substituents in cyclopalladation of ferrocenylhydrazones
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The syntheses and characterization of seven novel ferrocenylhydrazones of general formulae: [(η5-C5H5)Fe{(η5-C 5H4)-CH=N-NH(R)}] {with R = C6H4-4-Cl (1a), C6H4-4-NO2 (1b), C6H5 (1c), C6H3-2,4-(NO2)2 (1d), C6H3-2,5-(Cl)2 (1e), C6F5 (1f) or C6H4-2-CH3 (1g)} are reported. We also describe the reactions of compounds 1 with PdCl2 in refluxing ethanol, by which different cyclopalladated complexes containing σ(Csp2, aryl-Pd), σ(Csp2, ferrocene-Pd) or σ(Csp3-Pd) bonds were obtained. A comparative study of the ease by which a σ(Csp2, ferrocene-H) or a σ(Csp2, aryl-H) bond in compounds 1 and in the ferrocenylhydrazones: [(η5-C5H5)Fe{(η5-C 5H4)-C(CH3)=N-NH(R)}] (1′) {derived from acetylferrocene} were to be activated is also reported.
- Lopez, Conception,Granell, Jaume
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- Metal coordination mediated reversible conversion between linear and cross-linked supramolecular polymers
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(Figure Presented) The dynamic duo: Different topologies of dynamic supramolecular polymers, such as linear (see picture, left) and crosslinked species (right), can be reversibly interconverted by external stimuli that utilize host-guest and metal-ligand
- Wang, Feng,Zhang, Jinqiang,Ding, Xia,Dong, Shengyi,Liu, Ming,Zheng, Bo,Li, Shijun,Wu, Ling,Yu, Yihua,Gibson, Harry W.,Huang, Feihe
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- Regioselectivity in the Sonogashira coupling of 4,6-dichloro-2-pyrone
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The Sonogashira cross-coupling of 4,6-dichloro-2-pyrone with terminal acetylenes proceeds in good yields and high regioselectivity for the 6-position; dibenzylidene acetone (dba) type ligands play a non-innocent role in reactions mediated by Pd(dba)2/PPh3; theoretical studies indicate that C-6 oxidative addition is favoured both kinetically and thermodynamically.
- Fairlamb, Ian J. S.,O'Brien, Ciara T.,Lin, Zhenyang,Lam, King Chung
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- Dinuclear PdII/PtIIcomplexes [M2(phosphine)n(thio-ligand)3]Cl incorporating N,S-bridged pyridine-2-thiolate and benzimidazoline-2-thiolate
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Equimolar reaction of [PdCl2(dppm)] {dppm?=?bis(diphenylphosphino) methane} with pyridine-2-thione (pySH) in presence of NaOH base in aqueous ethanol formed dinuclear mixed-ligand complex, [PdII2(μ-κ2:N,S-pyS)3(μ-P,P-dppm)]Cl 1. Similarly, reaction of PdCl2(PPh3)2with benzimidazoline-2-thione (bzimSH) in 1:2?M ratio in the presence of Et3N base in acetonitrile has formed a dinuclear complex, [PdII2(μ-κ2:N,S-bzimS)2(κ1-S-bzimS)(PPh3)3]Cl·2H2O 2. Surprisingly, analogous thio-ligand, 1,3-imidazoline-2-thione (imzSH), merely formed a simple square planar complex, [Pd(κ1-S-imzSH)4]Cl2·2H2O 3. The reaction of H2PtCl6with pySH and dppm (1:1:1?M ratio) in the presence of Et3N base in toluene–ethanol (1:1:: v/v) mixture also formed a mixed-ligand dinuclear complex [PtII2(μ-κ2:N,S-pyS)3(μ-P,P-dppm)]Cl similar to 1. All these complexes have been characterized using analytical data, IR, NMR (1H,31P), UV–vis, fluorescence, ESI-mass and single crystal X-ray crystallographic techniques. The anionic thio-ligands are N,S-bridged in complexes 1 and 4, both N,S-bridged and κ1-S bonded in 2 and as neutral κ1-S bonded in 3. There are short M?M contacts in 1 and 4 (1: 2.7249(5) ? 4: 2.7350(8) ?). Complexes 1, 3 and 4 showed intense fluorescence. ESI mass spectral studies of 1, 3 and 4 revealed the formation of molecular ions and other species.
- Lobana, Tarlok S.,Sandhu, Amanpreet K.,Mahajan, Rakesh K.,Hundal, Geeta,Gupta, Sushil K.,Butcher, Ray J.,Castineiras, Alfonso
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- Quasi-homogeneous catalytic conversion of CO2into quinazolinones inside a metal-organic framework microreactor
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Management of CO2 has been attracting great attention in this century. Reaction of CO2 with 2-haloanilines and isocyanides is an attractive way for both converting CO2 and producing quinazolinones, which are key intermediates for the synthesis of various biologically active products. However, the heterogeneous and relatively inert nature of CO2 with 2-haloaniline and isocyanide reactants limits the types of suitable catalysts. Herein, we use metal-organic frameworks (MOFs) as a microreactor , in which Pd(PPh3)2Cl2 is well-dispersed as a single-molecular catalyst, and the reactants react in the molecular level through a quasi-homogeneous way to convert CO2 into quinazolinones under mild conditions with both promising yields over homogeneous catalysts and good recyclability as a heterogeneous reaction. The MOF-assisted single-molecular catalysis strategy should contribute to CO2 conversion, production of quinazolinone-type bioactive intermediates, and the epochal development of homo-and-heterogeneous catalysis. This journal is
- Cheng, Peng,Gao, Jianbo,Ma, Jian-Gong,Zhou, Zhenzhen
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- Schiff base triphenylphosphine palladium (II) complexes: Synthesis, structural elucidation, electrochemical and biological evaluation
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The complexes N-(2-oxidophenyl)salicylideneiminatotriphenylphosphine palladium(II) (1) and N-(2-sulfidophenyl)salicylideneiminato triphenylphosphine palladium(II) (2) of tridentate Schiff bases derived from salicylaldehyde and an amino- or thiophenol, have been synthesized and characterized by various spectroscopic, analytical and electro-analytical techniques. X-ray single crystal analysis of complex 1 has revealed its square planar geometry. The thermal analysis has shown the absence of coordinated water and final degradation product is PdO. The alkaline phosphatase studies have indicated that enzymatic activity is concentration dependent which is inversely proportional to the concentration of the compounds. The biological assays (brine shrimp cytotoxicity, DPPH) have reflected their biologically active and mild antioxidant nature. However, results of DNA protection assay have shown that they possess moderate protective activity against hydroxyl free radicals (OH). The voltammetric studies ascertain two-electron reduction of the compounds through purely diffusion controlled process and reveal intercalative mode of drug DNA interactions.
- Shabbir, Muhammad,Akhter, Zareen,Ahmad, Iqbal,Ahmed, Safeer,Shafiq, Maryam,Mirza, Bushra,McKee, Vickie,Munawar, Khurram Shahzad,Ashraf, Ahmad Raza
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- Reactivity of [PdCl(bdtp)](BF4) with monodentate neutral and anionic ligands. Structure of [Pd(bdtp)(PPh3)](BF4)2 (bdtp = 1,5-bis(3,5-dimethyl-1-pyrazolyl)-3-thiapentane)
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Complex [PdCl(bdtp)](BF4), in presence of AgBF4 or NaBF4, reacts with pyridine (py), triphenylphosphine (PPh3), cyanide (CN-), thiocyanate (SCN-) or azide (N3-) ligand
- de León, Antonio,Pons, Josefina,García-Antón, Jordi,Solans, Xavier,Font-Bardía, Mercè,Ros, Josep
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- Interaction of palladium(II) complexes with amino-alcohols: Synthesis of new amino-carbonyl complexes, key intermediates to cyclic carbamates
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The interaction between carbon monoxide and aromatic or aliphatic amino-alcohols promoted by some palladium(II) tetracoordinated complexes, stabilized by aryl mono- and diphosphines [triphenylphosphine (PPh3); 1,2-bis(diphenylphosphine)ethane (dppe)], an amino-phosphine [(2-(/3-diphenylphosphino)ethylpyridine) (PN)], and diamines [2,2′-dipyridine (dipy); 1,10-phenanthroline (phen)], was investigated. All tested complexes and substrates were shown to interact with CO to afford either stable carbamoyl complexes, which were isolated and studied for their reactivity, or, directly, organic products. From the reaction of PdCl 2(PN) with 4-aminophenol (4-APhOH, a) the stable carbamoyl complex (PN)PdCl(CONHC6H4-OH), able to release the amino-carbonyl ligand as isocyanate HOC6H4NCO, was isolated. The aliphatic amino-alcohols H2N-R-OH [2-aminoethanol (2-AE, b); 1-amino-2-propanol (1-A2P, c); 3-aminopropanol (3-AP, d); 2-aminobutanol (2-A1B, e); 4-aminobutanol (4-AB, f); 5-aminopentanol (5-APE, g); 6-aminohexanol (6-AHX, h)] were reacted with all Pd complexes described above, but only when the triphenylphosphine ligand was used was it possible to isolate the stable carbamoyl complexes (PPh3)2PdCl(CONH-R-OH). The Pd(II) complexes with other ligands reacted in the same way, but the relevant intermediate complexes decomposed during the progress of the reaction, giving a mixture of cyclic carbamates and ureas and the relevant Pd(0) complex, "Pd-L" (L = PN, dppe, dipy, phen), which converted into Pd-black and the free ligand. Carbamoyl complexes with an aliphatic amino-alcohol bearing a primary amine are unprecedented in the literature. They were characterized by means of IR and NMR spectroscopy and studied for their reactivity. All the complexes upon simple heating or by reaction with I2 or CuCl 2 release the amino-carbonyl function as cyclic carbamate and/or urea, depending on the complex and the presence or absence of the free amino-alcohol in solution.
- Giannoccaro, Potenzo,Dibenedetto, Angela,Gargano, Michele,Quaranta, Eugenio,Aresta, Michele
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- Palladium catalyzed hydrodechlorination of α-chloroacetophenones by hydrogen transfer from the H2O-CO system
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PdCl2(PPh3)2, in combination with an extra amount of PPh3, is an excellent catalyst precursor for the hydrodechlorination of α-chloroacetophenone to acetophenone by hydrogen transfer from the H2O-CO system. The reaction occurs with concomitant evolution of CO2. Under typical reaction conditions (50-70°C, 40-80 atm, substrate/Pd/P = 2000/1/50, H2O/substrate = 8-12/1), the reaction occurs in 70-80% yield in 2 h, using ethanol or dioxane as a solvent ([Pd] = 5.10-4 mol · l-1). When the catalyst precursor is employed without adding an additional amount of PPh3 extensive decomposition to metallic palladium occurs. Also Pd/C is active in promoting the hydrodechlorination reaction. As expected the reaction rate increases upon increasing concentration of catalyst, carbon monoxide pressure and temperature. The yield is slightly influenced by the concentration of the substrate. The effect of the concentration of H2O is the most significant. In ethanol as a solvent at low concentration of water the reaction rate increases to reach a plateau above 6-7 10-2 mol · l-1 of water. On the basis of the fact that it is known that (i) the precursor is reduced to a Pd(0) species by the H2O-CO system, even in the presence of hydrochloric acid, which is freed during the course of the hydrodechlorination reaction and that (ii) the starting α-chloroacetophenone oxidatively adds to Pd(0) to give Pd(CH2COPh)Cl(PPh3)2 (I) and that (iii) this complex reacts with hydrochloric acid to give acetophenone and PdC12(PPh3)2 (II), it is proposed thai the hydrodechlorination reaction proceeds via the intermediacy of a species analogous to complex (I) and that (II) is reduced to the Pd(0) complex through the intercation of CO and H2O with the metal center to give a species having a Pd-(COOH) moiety, which after β-hydride abstraction gives a palladium-hydride species with concomitant evolution of CO2. The hydride gives off a proton and reduces Pd(II) returning a Pd(0) species back to the catalytic cycle. We found also that complex (I) is reduced to a Pd(0) complex with formation of acetophenone through the action of H2O and CO. It is proposed that this reaction, which may be at the base of a different catalytic path, occurs via the intermediacy of a species having a H-Pd-(CH2COPh) which, after reductive elimination of acetophenone give the Pd(0) complex starting a new catalytic cycle. In the case of the Pd/C catalyzed hydrodechlorination it is suggested that H2O and CO interacts on the surface of the metal to give a hydride and evolution of CO2 and that this hydride displaces a chloride anion from α-chloroacetophenone absorbed on the catalytic surface to give the hydrodechlorination product.
- Cavinato,Pasqualetto,Ronchin,Toniolo
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- Catalytic carbonylation of 4-penten-1-ol to ε-caprolactone and oligocaprolactone
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A catalyst consisting of Pd2(dba)3 + 2 XANTPhos (dba = dibenzylideneacetone, XANTPhos = 9,9-dimethyl-4,5-bis(diphenylphosphino) xanthene) in toluene catalyzes the alkoxycarbonylation of 4-penten-1-ol to form the cyclic products ε-caprolactone and 2-methylvalerolactone, as well as oligocaprolactone. The conversion and selectivity observed using this catalyst is higher than that observed with other reported systems with the regioselectivity for terminal carbonylation exceeding 70%.
- Funk, Jeffrey K.,Newsham, David K.,Goldstein, David N.,Liu, Shengsheng,Sen, Ayusman
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- UNUSUAL REARRANGEMENT OF ?-VINYLPALLADIUM COMPLEXES INTO η2-OLEFIN COMPLEXES. THE STRUCTURE OF (η2-1-TRIPHENYLPHOSPHONIUM-2-CARBOMETHOXYETHYLENE)-(TRIPHENYLPHOSPHINE)IODOPALLADATE
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β-Substituted ?-vinylpalladium complexes (I) (X = Cl, I; R = Me, Et) have been obtained by interaction of the E- and Z-β-halogen acrylates with tetrakis(triphenylphosphine)palladium.On heating complexes I rearrange into isomeric η2-olefin-ylidepalladium complexes (II).The structure of these complexes has been established by X-ray study of the compound with X = I, R = Me.
- Rybin, L. V.,Petrovskaya, E. A.,Rubinskaya, M. I.,Kuz'mina, L. G.,Struchkov, Yu.T.,et al.
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- Palladium-Catalyzed Formal Insertion of Carbenoids into Aminals via C-N Bond Activation
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A new strategy for selective insertion of metal carbenes into C-N bond has been developed via Pd-catalyzed C-N bond activation. A series of aminals and α-diazoesters with different substituents were successfully incorporated even in 0.1 mol % of catalyst under mild conditions, affording a wide range of α,β-diamino acid esters with quarternary carbon-centers. Preliminary mechanistic studies uncovered that the unique electrophilic cyclopalladated species could easily react with diazoacetates to generate a Pd-carbenoid intermediate which was involved in the catalytic cycle.
- Qin, Guiping,Li, Lixin,Li, Jiawen,Huang, Hanmin
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- Convergent synthesis of alkynylbis(bidentate phosphine)ruthenium dendrimers
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The convergent synthesis of alkynylbis(bidentate phosphine)ruthenium dendrimers was discussed. The nonlinear optical (NLO) properties of alkynylmetal complexes were also examined. It was demonstrated that electron-rich organometallic dendrimers with metals dispersed through the dendritic structures were synthetically accessible.
- McDonagh, Andrew M.,Powell, Clem E.,Morrall, Joseph P.,Cifuentes, Marie P.,Humphrey, Mark G.
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- Fluoride-assisted reduction of palladium(II) phosphine complexes
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PdCl2 in the presence of chelating or monodentate arylphosphines reduces in high yields to give Pd(O) phosphine complexes when the reaction is carried out in the presence of n-Bu4NF·3H2O.
- Mason, Mark R.,Verkade, John G.
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- Thermodynamically stable, highly emissive poly(diphenylacetylene) derivative containing long alkyl side chain without silylene linkage
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A PDPA derivative with a long alkyl side chain connected directly onto the backbone (1) was synthesized and compared to a corresponding polymer with a silylene linkage between the side chain and the backbone (2). Polymers 1 and 2 showed similar solubilities: both polymers dissolved well in organic solvents such as toluene, THF, and chloroform but not in polar solvents such as DMF and alcohols. When cast from toluene solutions, smooth and transparent films were readily obtained. Thermogravimetric analysis showed that 1 was more thermally stable than 2 owing to the absence of the relatively weak silylene linkage. Differential scanning calorimetry showed that 1 exhibited a local thermodynamic relaxation due to the long alkyl side chains at a higher temperature than 2. In photoluminescence spectroscopy, 1 was found to be more emissive, with quantum yields being as high as 63.1 and 27.4% in solution and films, respectively, while those of 2 were 49.4 and 20.6%. Consequently, 1 was more thermally stable, stiffer, and more emissive than 2.
- Jin, Young-Jae,Kawamura, Yuto,Teraguchi, Masahiro,Aoki, Toshiki,Kwak, Giseop
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- Charge-Assisted phosph(v)azane anion receptors
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Coordination of Cu(i) or Pd(ii) to seleno-cyclodiphosph(v)azanes of the type [RNH(Se)P(μ-NtBu)]2 results in positively charged anion receptor units which have increased anion affinity over the neutral seleno-phosph(v)azanes, due to the increase in electrostatic interactions between the receptor and the guest anions. The same effect is produced by replacement of one of the PSe units by a P-Me+ unit.
- Bond, Andrew D.,Goodman, Jonathan M.,Lee, Sanha,Plajer, Alex J.,Wright, Dominic S.
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- Mixed ligand cobalt and palladium complexes containing triphenylphosphine and a hydrazone: Synthesis and application in non-linear optics
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Mixed ligand complexes of cobalt and palladium containing triphenylphosphine and a hydrazone derived from furfural and hydrazine hydrate have been designed, synthesized, evaluated, and characterized from their spectral properties, elemental analysis, and magnetic susceptibility measurements. The spectral techniques suggest that the complexes exhibit square planar geometry. The monomeric properties of the complexes are evaluated from their magnetic susceptibility values. The complexes were subjected to z-scan analysis for third-order non-linear optical measurements. Non-linear transmission measurements performed using laser pulses at 532 nm in nanosecond indicate that the complexes may show good potential as optical limiters.
- Ramakrishna, Dileep
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- Synthesis of a diferrocenylvinylidene complex by migration of a ferrocenyl substituent
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An unusual 1,2-ferrocenyl migration has been observed following reactions of [Ru(dppe)Cp][BArF4] with diferrocenylacetylene, extending the scope of group rearrangments beyond methyl (Wagner-Meerwein) and phenyl entities. Ferrocene-containing bis(alkynes) RCCArCCR (R = Fc, Ar = 1,4-phenylene; R = Ph, Ar = 1,1′-ferrocenylene) gave bimetallic bis(vinylidene) complexes following two consecutive rearrangements.
- Korb, Marcus,Moggach, Stephen A.,Low, Paul J.
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supporting information
p. 4251 - 4254
(2021/05/05)
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- Rip It off: Nitro to Nitroso Reduction by Iron Half-Sandwich Complexes
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Activation of [FeCl(dppe)Cp] (1) by chloride abstraction with Na[BArX4] (X = F, [B(3,5-(CF3)2-C6H3)4]; X = Cl, [B(3,5-Cl2-C6H3)4]) permits reactions with a range of nitro aromatics, RC6H4NO2 (R = halogen, Me, OMe, NO2 or NMe2), to give the cationic iron nitroso complexes [Fe{N(O)-C6H4R}(dppe)Cp][BArX4]) ([3][BArX4]). Similar reactions of 1 and Na[BArX4] with [Fe(NCC6H4NO2)(dppe)Cp][BArX4] gave bimetallic [{Fe(dppe)Cp}2{μ-NCC6H4N(O)}][BArF4]2. However, reactions of 1 and Na[BArX4] with 4-nitrophenol gave the first example of the bench-stable iron half-sandwich phenolate complex [Fe(OC6H4NO2)(dppe)Cp]+ rather than NO2 activation. The formation of complexes [3]+ likely proceeds via the unusual blue bimetallic species [{Fe(dppe)Cp}2{μ,κ2O,O′-O2NAr}]2+. This compound undergoes N-O bond cleavage, resulting in [3]+ and a FeIV=O species, which reacts via an internal C-H activation of the dppe ligand to give [FeIII(κ3O,P,P′-P(2-O-C6H4)(Ph)-C2H4-PPh2)Cp]+. Complexes [3]+ are stable under ambient conditions, are readily purified by column chromatography and can be isolated in up to 50% yield, considering that 0.5 equiv of 1 is required as the oxygen acceptor.
- Korb, Marcus,Hosseini Ghazvini, Seyed Mohammad Bagher,Moggach, Stephen A.,Meunier, Jean-Fran?ois,Bousseksou, Azzedine,Low, Paul J.
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supporting information
p. 4986 - 4995
(2021/04/06)
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- Epoxyanthracene Derivatives and Dicarbonylation on Benzene Ring via Hexadehydro-Diels-Alder (HDDA) Derived Benzynes with Oxazoles
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A capture reaction of hexadehydro-Diels-Alder (HDDA) derived benzyne with various substituted oxazoles is reported. With methyl, hydrogen, or phenyl as the substituent at 2-position of oxazole, tetraynes afforded epoxyanthracene derivatives or underwent dicarbonylation on benzene ring. The reaction does not require any catalyst or additive. The mechanism behind the reaction was investigated. The obtained polycyclic product structure has potential application value in optoelectronic materials. The availability of dicarbonylated arene implies the uniqueness of HDDA benzyne reaction compared with traditional benzyne.
- Hu, Qiong,Hu, Yimin,Lei, Yu,Yang, Feihu,Zheng, Xiaojie,Zhu, Wenjing
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supporting information
(2021/11/22)
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- Preparation method of bis (triphenylphosphine) palladium dichloride
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The invention discloses a preparation method of bis (triphenylphosphine) palladium dichloride, which comprises the following steps of: (a) adding palladium powder into an aqua regia solution, stirring, heating, dissolving, adding hydrochloric acid while the solution is hot to drive nitrate, cooling, and adding an ethanol-water mixed solution for dilution; (b) dissolving triphenylphosphine in an organic solvent to obtain an organic solution of triphenylphosphine; and (c) dropwise adding the solution obtained in the step (a) into the solution obtained in the step (b), stirring for reaction, andthen cooling, filtering, washing, draining and vacuum drying to obtain the target product bis (triphenylphosphine) palladium dichloride. The initial raw material palladium powder directly replaces palladium dichloride, the target product is directly synthesized, the synthesis period is shortened, the operation steps are simple, the efficiency is improved, the production cost is reduced, the yieldof the target product is larger than 99.5%, and the purity of the target product is larger than 98.0%.
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Paragraph 0028-0045
(2021/02/06)
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- Fully Substituted Conjugate Benzofuran Core: Multiyne Cascade Coupling and Oxidation of Cyclopropenone
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An unprecedented C═C double bond cleavage of cyclopropenone and dioxygen activation by multiyne cascade coupling has been developed. This chemistry provides a novel, simple, and efficient approach to synthesize fully substituted conjugate benzofuran derivatives from simple substrates under mild conditions. The density functional theory (DFT) calculations reveal that the unique homolytic cleavages of cyclopropenone and molecular oxygen are crucial to the success of this reaction.
- Yao, Liangliang,Hu, Qiong,Bao, Li,Zhu, Wenjing,Hu, Yimin
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supporting information
p. 4971 - 4975
(2021/06/30)
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- Access to Benzoxazepines and Fully Substituted Indoles via HDDA Coupling
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The HDDA-derived benzyne intermediate was captured by oxazolines based on the addition reaction of benzyne to the Ca?N double bond. Benzoxazepine derivatives, fused benzoxazepine derivatives, and fully substituted indoles are synthesized in one step. The reaction does not require any catalyst or additives. Possible reaction mechanisms are presented.
- Zheng, Xiaojie,Liu, Baohua,Yang, Feihu,Hu, Qiong,Yao, Liangliang,Hu, Yimin
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supporting information
p. 956 - 959
(2020/02/15)
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- Phenanthrenes/dihydrophenanthrenes: The selectivity controlled by different benzynes and allenes
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A method for the intermolecular annulation of benzynes with allenes is disclosed. This protocol utilized allenes as an unconventional diene component for the selective synthesis of phenanthrenes and dihydrophenanthrenes under the control of different benzyne precursors, featuring high atom-economy and good functional group compatibility. Density functional theory (DFT) calculations reveal that different migratory routes of the aromatic C-H bond are crucial for the observed selectivity. This journal is
- Yao, Liangliang,Fang, Bo,Hu, Qiong,Lei, Yu,Bao, Li,Hu, Yimin
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supporting information
p. 15185 - 15188
(2020/12/21)
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- Selective Oxidative Carbonylation of Aniline to Diphenylurea with Ionic Liquids
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A catalytic system for the selective oxidative carbonylation of aniline to diphenylurea based on Pd complexes in combination with imidazolium ionic liquids is presented. Both oxidants, Pd complexes, and ionic liquids affect the activity of the reaction, and the choice of oxidant determines the selectivity of the reaction. Together they allow the reaction to proceed under comparatively mild conditions without a loss of activity. Examination of the reaction by use of in situ NMR spectroscopy allowed us to observe an intermediate suggested only previously, which supported the proposed mechanism.
- Zahrtmann, Nanette,Claver, Carmen,Godard, Cyril,Riisager, Anders,Garcia-Suarez, Eduardo J.
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p. 2450 - 2457
(2018/04/11)
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- Oxidative Mechanochemistry: Direct, Room-Temperature, Solvent-Free Conversion of Palladium and Gold Metals into Soluble Salts and Coordination Complexes
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Noble metals are valued, critical elements whose chemical activation or recycling is challenging, and traditionally requires high temperatures, strong acids or bases, or aggressive complexation agents. By using elementary palladium and gold, demonstrated here is the use of mechanochemistry for noble-metal activation and recycling by mild, clean, solvent-free, and room-temperature chemistry. The process leads to direct, efficient, one-pot conversion of the metals, including spent catalysts, into either simple water-soluble salts or metal–organic catalysts.
- Do, Jean-Louis,Tan, Davin,Fri??i?, Tomislav
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supporting information
p. 2667 - 2671
(2018/02/06)
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- Synthesis and characterization of four new complexes of Cu(I), Cu(II), Ir(III) and Pd(II) formed by CS2 insertion in L2MXn (L = PPh3 and imidazole, X = Cl, n = 2,3)
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Four new complexes [L2Cu(S2COC2H5)] {L=PPh3 (A), C3H4N2 (B)}, [L2IrCl2(S2COC2H5)] (L=PPh3) (C) and [L2Pd(S2COC2H5)] (L=PPh3) (D) have been synthesized by the insertion of CS2 in L2CuCl2, L3IrCl3 and L2PdCl2, respectively in mixed solvent of dichloromethane and ethanol at room temperature. The complexes have been characterized by FTIR, UV-visible and ESR spectroscopy. All the complexes have been found to be air-stable. Complexes (A), (B) and (D) are distorted square planar while complex (C) is of distorted octahedral geometry.
- Sultana, Samim,Gogoi, Pradip K.
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p. 2285 - 2288
(2018/09/10)
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- Synthesis and catalytic application of Pd complex catalysts: Atom-efficient cross-coupling of triarylbismuthines with haloarenes and acid chlorides under mild conditions
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Palladium-catalysed cross-coupling reactions are some of the most frequently used synthetic tools for the construction of new carbon–carbon bonds in organic synthesis. In the work presented, Pd(II) complex catalysts were synthesized from palladium chloride and nitrogen donor ligands as the precursors. Infrared and 1H NMR spectroscopic analyses showed that the palladium complexes were formed in the bidentate mode to the palladium centre. The resultant Pd(II) complexes were tested as catalysts for the coupling of organobismuth(III) compounds with aryl and acid halides leading to excellent yields with high turnover frequency values. The catalysts were stable under the reaction conditions and no degradation was noticed even at 150°C for one of the catalysts. The reaction proceeds via an aryl palladium complex formed by transmetallation reaction between catalyst and Ar3Bi. The whole synthetic transformation has high atom economy as all three aryl groups attached to bismuth are efficiently transferred to the electrophilic partner.
- Jadhav,Pardeshi
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- Synthesis and Reactivity of Selones and Dihaloselones: Complexation of Selones with d8- and d10-Metal Ions
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The reactivities of the monodentate selone LSe (L = 1,3-dibutylbenzimidazol-2-ylidene; 10a), the bidentate pyridine-functionalized selone L′Se (L′ = 1-pyridyl-3-butylimidazol-2-ylidene; 10b) and the multidentate ether-functionalized selone L′′Se {L′′ = 1,3-bis[2-(2-methoxyethoxy)ethyl]benzimidazol-2-ylidene; 10c} with soft transition-metal halides (PdX2, PtX2, ZnX2, CdX2 and HgX2; X = Cl, Br, I) are probed. Compounds 10a and 10c react with metal halides to give complexes of the type [Cu2(μ-X)2(LSe)2] (X = Br, I; 11, 12), [MX2(LSe)2] (13–22) or [M2X2(μ-X)2(L′′Se)2] (X = Cl, Br, I; 26–32), whereas 10b and HgX2 (X = Cl, Br, I) form 1:1 complexes HgX2(L′Se) (21–23), in which the pyridine moiety coordinates to the metal centre to form a six-membered chelate. The reactivity of 10a was compared with those of triphenylphosphine and triethylamine. The reaction of 10c with molecular iodine yields the diiodoselone L′′SeI2 (35), which disproportionates to give the selone adduct of the iodonium ion, [(L′′Se)2I]+I3– (36). The reactions of LSeX2 [X = Cl (34a), Br (34b), I (34c)] with organotellurium compounds, namely, tellone LTe (10d) and diphenyl telluride (37), afford the dihalotellones LTeX2 [X = Cl (38a), Br (38b), I (38c)] and Ph2TeX2 [X = Cl (39a), Br (39b), I (39c)], respectively. The oxidizing properties of LSeX2 (34a–34c) were investigated with rare-earth metals.
- Yadav, Sangeeta,Singh, Harkesh B.,Butcher, Ray J.
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p. 2968 - 2979
(2017/06/28)
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- Palladium(II) complexes bearing mixed N^N^X (X?=?O and S) tridentate ligands as pre-catalysts for the methoxycarbonylation of selected 1-alkenes
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The methoxycarbonylation of selected 1-alkenes catalyzed by various neutral and cationic palladium(II) complexes, containing mixed N^N^X (X = O and S) tridentate ligands 2-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-6-(phenoxymethyl)pyridine (L1), 2-[(3,5-di-tert-butyl-1H-pyrazol-1-yl)methyl]-6-(phenoxymethyl)pyridine (L2), 2-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-6-(phenylthiomethyl)pyridine (L3), 2-[(3,5-di-tert-butyl-1H-pyrazol-1-yl)methyl]-6-(phenylthiomethyl)pyridine (L4), has been investigated. Neutral complexes, [(?2-L1)Pd(CH3)(Cl)] (1a), [(?2-L2)Pd(CH3)(Cl)] (2a), [(?2-L3)Pd(CH3)(Cl)] (3a), [(?2-L4)Pd(CH3)(Cl)] (4a), and the salts, [(?3-L3)Pd(CH3)][BAr4F] (3c) and [(?3-L4)Pd(CH3)][BAr4F] (4c), underwent complete decomposition during the reaction to palladium black and showed no catalytic activity. However, the addition of PPh3 to the reaction dramatically increased the catalytic activity. On the other hand, the salts, [(?2-L1)Pd(CH3)(PPh3)][BAr4F] (1b), [(?2-L2)Pd(CH3)(PPh3)][BAr4F] (2b), [(?2-L3)Pd(CH3)(PPh3)][BAr4F] (3b) and [(?2-L4)Pd(CH3)(PPh3)][BAr4F] (4b), showed good conversion of the selected olefins to branched and linear esters without PPh3. Addition of PPh3 to reactions with 1b-4b significantly improved catalytic activity. All decomposition of complexes led to the formation of the known palladium complexes, [Pd(PPh3)2(Cl)(CH3)] and [Pd(PPh3)2Cl2]. The decomposition of all palladium complexes could be followed by NMR studies and [Pd(PPh3)2Cl2] could be isolated from the crude methoxycarbonylation reaction.
- Kumar, Kamlesh,Darkwa, James
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p. 249 - 257
(2017/10/27)
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- Synthesis, structural characterization and biological screening of heteroleptic palladium(II) complexes
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Heteroleptic palladium(II) complexes of the type formula [(DTC)(Pd)(PR3)Cl], where DTC = bis(2-ethylhexyl)dithiocarbamate (1, 8, 9, 10), bis(2-methoxyethyl)dithiocarbamate (2), di-n-decyldithiocarbamate (3, 6), di-n-hexyldithiocarbamate (4, 7), bis(2-methylbutyl)dithiocarbamte (5); PR3 = diphenyl-t-butylphosphine (1), diphenyl-n-propylphosphine (2), triphenylphosphine (3, 4, 5, 10), diphenyl-p-tolylphosphine (6, 7, 8), diphenylbenzylphosphine (9); have been synthesized and characterized by FTIR, Raman, multinuclear and multinuclear NMR (1H, 13C, 31P) spectroscopy and elemental analyses. The structures of complexes (1 and 2) were determined by single-crystal X-ray diffraction. The geometries around the metal centers are pseudo square-planar. The new complexes exhibit moderate anticancer and antibacterial activity.
- Khan, Hizbullah,Badshah, Amin,Said, Muhammad,Murtaza, Ghulam,Sirajuddin, Muhammad,Ahmad, Jamil,Butler, Ian S.
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p. 176 - 182
(2016/05/09)
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- Fused Selenazolinium Salt Derivatives with a Se-N+ Bond: Preparation and Properties
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Convenient methods for the preparation of stable, fused selenazolinium salt systems with a Se-N+ bond have been developed. The mechanism for the formation of the selenazole cycle was investigated in detail by conducting multinuclear NMR experiments. The ability of these compounds to form stable inner salts was demonstrated. We have shown the glutathione peroxidase (GPx) like properties of selenazolopyridinium salts by oxidizing sulfur-containing natural amino acids, as well as aromatic and heteroaromatic aldehydes. The molecular structures of most of the compounds were confirmed by X-ray diffraction studies.
- Arsenyan, Pavel,Vasiljeva, Jelena,Belyakov, Sergey,Liepinsh, Edvards,Petrova, Marina
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supporting information
p. 5842 - 5855
(2015/09/15)
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- Photocatalytic Dehydrogenative Lactonization of 2-Arylbenzoic Acids
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A metal-free dehydrogenative lactonization of 2-arylbenzoic acids at room temperature was developed. This work illustrates the first application of visible-light photoredox catalysis in the preparation of benzo-3,4-coumarins, an important structural motif in bioactive molecules. The combination of photocatalyst [Acr+-Mes] with (NH4)2S2O8 as a terminal oxidant provides an economical and environmentally benign entry to different substituted benzocoumarins. Preliminary mechanistic studies suggest that this reaction most likely occurs through a homolytic aromatic substitution pathway.
- Ramirez, Nieves P.,Bosque, Irene,Gonzalez-Gomez, Jose C.
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supporting information
p. 4550 - 4553
(2015/09/28)
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- Kinetics and mechanisms of homogeneous catalytic reactions. Part 12. Hydroalcoxycarbonylation of 1-hexene using palladium/triphenylphosphine systems as catalyst precursors
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Systems prepared in situ by addition of n equivalents of triphenylphosphine to palladium dichloride in the presence of m equivalents of para-toluenesulfonic acid (TSA), PdCl2/nPPh3/mTSA (n and m varying between 2 and 10), were used as precatalysts for the olefin carbonylation (1-hexene, cyclohexene and styrene) with alcohols (MeOH, EtOH, n-PrOH and i-PrOH) to generate the corresponding esters (hydroalcoxycarbonylation), under mild reaction conditions. For 1-hexene carbonylation in presence of methanol (1-hexene hydromethoxycarbonylation), the most active system was PdCl2/6PPh3/5TSA at P(CO) = 50 atm and T = 125°C, which was also active for the hydromethoxycarbonylation of other olefins (1-hexene > styrene > cyclohexene). This system was regioselective towards the linear product for 1-hexene and towards the branched product for styrene. A kinetic study of 1-hexene hydromethoxycarbonylation catalyzed by PdCl2/6PPh3/5TSA showed that the initial reaction rate (ro) was first order on Pd and MeOH concentrations and fractional order with respect to CO concentration; for olefin concentration was found a saturation curve. These kinetic results, together with coordination chemistry and computational DFT studies, allow us to propose a catalytic cycle involving species of the type [Pd(H)(L)(PPh3)2]+n (L = Cl, n = 0; L = CO, MeOH, olefin and PPh3, n = 1) as the catalytically active species and three sequential reactions: (1) olefin insertion into the Pd-H bond to yield Pd-alkyl species, (2) CO insertion into the Pd-C bond to generate Pd-acyl intermediates, and (3) the methanolysis of Pd-acyl species to produce the corresponding methyl esters, regenerate the active species and restart the cycle; the last reaction is considered the rate-determining step (rds) of the mechanism.
- Rosales, Merln,Pacheco, Ins,Medina, Jairo,Fernndez, Juan,Gonzlez, ngel,Izquierdo, Rodolfo,Melean, Luis G.,Baricelli, Pablo J.
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p. 1717 - 1727
(2015/02/19)
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- Palladium-catalyzed suzuki carbonylative reaction of α-Halomethyl oxime ethers: A regioselective route to unsymmetrical 1,3-oxyiminoketones
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The three-component reaction of a-halomethyl oxime ethers, boronic acids and carbon monoxide at atmospheric pressure catalyzed by tetrakis- (triphenylphosphine)palladium(0) gives efficiently unsymmetrical β-alkoxyimino carbonyl compounds with total control of the regioselectivity, in high yield and atomic economy. Simple commercially available starting materials are used in this synthetic procedure. The three components assembly takes place preferentially versus the competing direct coupling or other possible side reactions. The mechanism of the transformation was investigated by NMR and intermediate palladium(II) complexes were detected.
- Noverges, Brbara,Medio-Simn, Mercedes,Asensio, Gregorio
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p. 3649 - 3658
(2015/01/09)
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- Palladium-catalyzed suzuki carbonylative reaction of a-halomethyl oxime ethers: A regioselective route to unsymmetrical 1,3-oxyiminoketones
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The three-component reaction of a-halomethyl oxime ethers, boronic acids and carbon monoxide at atmospheric pressure catalyzed by tetrakis- (triphenylphosphine)palladium(0) gives efficiently unsymmetrical b-alkoxyimino carbonyl compounds with total control of the regioselectivity, in high yield and atomic economy. Simple commercially available starting materials are used in this synthetic procedure. The three components assembly takes place preferentially versus the competing direct coupling or other possible side reactions. The mechanism of the transformation was investigated by NMR and intermediate palladium(II) complexes were detected.
- Noverges, Brbara,Medio-Simn, Mercedes,Asensio, Gregorio
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supporting information
p. 3649 - 3658
(2015/02/19)
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- Anticancer metallopharmaceutical agents based on mixed-ligand palladium(II) complexes with dithiocarbamates and tertiary organophosphine ligands
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Mixed-ligand palladium(II) complexes of the type [(DT)Pd(PR 3)Cl], where DT = diethyldithiocarbamate (1), dibutyldithiocarbamate (2,3), dipropyldithiocarbamate (4,5), bis(2-methoxyethyl)dithiocarbamate; PR3 = benzyldiphenylphosphine (1,4), diphenyl-o-tolylphosphine (2), diphenyl-t-butylphosphine (3), P-chlorodiphenylphosphine (5) and triphenylphosphine (6), have been synthesized and characterized by elemental analyses and FT-IR, Raman and multinuclear NMR spectroscopy. The structures of compounds 1 and 2 were determined by single-crystal X-ray diffraction (XRD) measurements and these analyses showed that the complexes have pseudo square-planar geometry around the Pd(II) and that the dithiocarbamate ligand is bound in a bidentate fashion, while the remaining two positions are occupied by a tertiary organophosphine and a chloride ligand. The anticancer studies showed that the Pd(II) complexes are highly active against cisplatin-resistant DU145 human prostate carcinoma (HTB-81) cells with the highest activity shown by compound 6 (IC50 = 2.12 μm). The redox behavior and ds-DNA-denaturing ability of the complexes were studied by cyclic voltammetry and two reduction and one oxidation waves were observed. The decrease in the reduction peak currents illustrated the consumption of the mixed-ligand drug by the DNA molecule. Copyright
- Khan, Hizbullah,Badshah, Amin,Said, Muhammad,Murtaza, Ghulam,Ahmad, Jamil,Jean-Claude, Bertrand J.,Todorova, Margarita,Butler, Ian S.
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p. 387 - 395
(2013/07/26)
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- Synthesis of a strained acetylenic macrocycle incorporating a para-oligo[2]cruciform bridge bent over nanoscopic dimensions: Structural, electronic, spectroscopic, and ion-sensing properties
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An Eglinton-Galbraith diethyne cyclization preferentially yielded a structurally unusual macrocycle, comprising a strained conjugated oligo[2]cruciform wire, forced into a 2.2 nm bow-shape by a terpyridine rein or tether, and stabilized towards light and heat by four insulating triisopropylsilylacetylene (TIPSA) substituents. Spectroscopic ion-binding studies revealed the macrocycle to exhibit a particularly high UV/Vis selectivity for PdII in dilute solution, and one of its precursors to afford a variety of luminescence quenching and color responses to particular metals, suggestive of promising ion-sensor applications. Under more concentrated conditions, the new macrocycle is able to bind specific metals (e.g., Au I) within its cavity despite the steric constraints. Intriguingly, variable-temperature (VT) UV/Vis/1H NMR investigations showed the TIPSA substituents to undergo restricted intramolecular motions along with reversible changes in the spectroscopic bandgap of the compound with temperature. In line with the theoretical calculations, the VT UV/Vis observations are consistent with a thermal modulation of the electronic conjugation through the strained oligo[2]cruciform bridge, which is coupled with redistributions within a mixture of conformational isomers of the macrocycle with differing relative twisting between the TIPSA-substituted phenyl rings. Overall, the generation of a para-oligo[2]cruciform, bent and flexed over nanoscopic dimensions through conformational tethering within the macrocyclic ring is noteworthy, and suggests a general approach to nanosized, curved, and strained, yet heat- and light-stable, para-phenyleneethynylene oligomers with unique physicochemical properties and challenging theoretical possibilities. Reining in the strain: An Eglinton-Galbraith diethyne cyclization yielded an unusual bow-shaped cycle (see scheme), incorporating a strained yet stable conjugated oligo[2]cruciform wire, bent over nanoscopic dimensions by a terpyridine tether. As well as spectroscopically sensing metal ions, it undergoes thermo-controllable bandgap changes in solution, consistent with hindered relative twisting of the substituted phenyl rings, thus functioning as an environmentally adaptive conjugation switch. Copyright
- Baxter, Paul N. W.,Gisselbrecht, Jean-Paul,Karmazin-Brelot, Lydia,Varnek, Alexandre,Allouche, Lionel
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supporting information
p. 12336 - 12349
(2013/09/23)
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- Donor-free phosphenium-metal(0)-halides with unsymmetrically bridging phosphenium ligands
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Reactions of (cod)MCl2 (cod = 1,5 cyclooctadiene, M = Pd, Pt) with N-heterocyclic secondary phosphines or diphosphines produced complexes [(NHP)MCl]2 (NHP = N-heterocyclic phosphenium). The Pd complex was also accessible from a chlorophosphine precursor and Pd2(dba) 3. Single-crystal X-ray diffraction studies established the presence of dinuclear complexes that contain μ-bridging NHP ligands in an unsymmetrical binding mode and display a surprising change in metal coordination geometry from distorted trigonal (M = Pd) to T-shaped (M = Pt). DFT calculations on model compounds reproduced these structural features for the Pt complex but predicted an unusual C2v-symmetric molecular structure with two different metal coordination environments for the Pd species. The deviation between this structure and the actual centrosymmetric geometry is accounted for by the prediction of a flat energy hypersurface, which permits large distortions in the orientation of the NHP ligands at very low energetic cost. The DFT results and spectroscopic studies suggest that the title compounds should be described as phosphenium-metal(0)-halides rather than conventional phosphido complexes of divalent metal cations and indicate that the NHP ligands receive net charge donation from the metals but retain a distinct cationic character. The unsymmetric NHP binding mode is associated with an unequal distribution of σ-donor/π-acceptor contributions in the two M-P bonds. Preliminary studies indicate that reactions of the Pd complex with phosphine donors provide a viable source of ligand-stabilized, zerovalent metal atoms and metal(0)-halide fragments.
- Foerster, Daniela,Nickolaus, Jan,Nieger, Martin,Benko, Zoltan,Ehlers, Andreas W.,Gudat, Dietrich
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p. 7699 - 7708
(2013/07/26)
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- Catalysts for Suzuki polycondensation: Ionic and "quasi-ionic" amphipathic palladium complexes with self-phase-transfer features
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Poly(9,9-dioctylfluorene) (PFO) with Mn values above 100 000 g mol-1 in a toluene/water system and Mn values up to 600 000 g mol-1 in a THF/water system has been obtained by improved Suzuki polycondensation using a new kind of amphipathic palladium catalyst with self-phase-transfer features, which could overcome the disadvantage caused by the immiscible biphasic mixture and accelerate the transmetalation step (see figure). Copyright
- Li, Jing,Fu, Hongwei,Hu, Pan,Zhang, Zilong,Li, Xiao,Cheng, Yanxiang
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supporting information
p. 13941 - 13944,4
(2020/09/16)
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- Pd complexes with trans-chelating ligands composed of two pyridyl groups and rigid π-conjugated backbone
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1,2-Bis(2-pyridylethynyl)benzene derivatives, having two pyridyl groups and π-conjugated backbone, were prepared from the 1:2 Sonogashira reaction of 1,2-diiodobenzene with 2-alkynyl pyridines. The obtained ligands react with the palladium(II) complexes such as [PdCl2(cod)] and [PdCl 2(MeCN)2] to form the complexes with the ligands coordinated in a trans-chelating bidentate mode. The ligand obtained from 1,3-diiodobenzene and 2-alkynyl pyridine bridges two Pd(II) centers, yielding a dipalladium complex. A dichloropalladium complex with the trans-chelating ligand, containing two methoxy groups in the central arylene group, promotes coupling of phenyl lithium and of phenyl acetylene to yield the respective homo-coupling products. The ligand displacement reactions of {bis(2-pyridylethynyl)benzene}palladium(II) complex with phosphine and dinitrogen ligands, such as PPh3, dppe, dppb, en, tmeda, bpy and phen, takes place smoothly to release the trans-chelating ligand.
- Jung, Miso,Suzaki, Yuji,Saito, Takashi,Shimada, Kyoichi,Osakada, Kohtaro
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p. 168 - 174
(2012/08/28)
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- η5-Cyclopentadienylpalladium(II) complexes: Synthesis, characterization and use for the vinyl addition polymerization of norbornene and the copolymerization with 5-vinyl-2-norbornene or 5-ethylidene-2-norbornene
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Dinuclear complexes of palladium(II), containing two bridging halogen (Cl or Br) ligands, [NnBu4]2[(X5C 6)2Pd(μ-Cl)2Pd(C6X 5)2] and [(X5C6)(L)Pd(μ-Y) 2Pd(C6X5)(L)] (X = F, Cl; Y = Cl, Br), readily react with cyclopentadienylthallium, C5H5Tl, to give the corresponding air stable half-sandwich, pseudo-trigonal η5- cyclopentadienylpalladium complexes, [NnBu4] [(η5-C5H5)Pd(C6X 5)2] (X = F 1, Cl 2) and (η5-C 5H5)Pd(C6X5)(L) (X = F, L = CNBut 3, PPh3 4, PMe2Ph 5, PEt3 6, AsPh3 7, SbPh3 8; X = Cl, L = PMe2Ph 9, PEt3 10), respectively. With tetraphenylcyclopentadienylthallium, C5Ph4HTl or pentabenzylcyclopentadienylthallium, C 5Bn5Tl (Bn = CH2Ph) the air stable half-sandwich complexes (η5-C5Ph4H) Pd(C6F5)(AsPh3), 12 and (η5- C5Bn5)Pd(C6F5)(AsPh3), 13 are synthesized accordingly. The molecular structures were verified by NMR-spectroscopy, X-ray crystallography (7, 12, 13) and electron impact-mass spectrometry (EI-MS). The precatalysts 4 and 7 can be activated with methylalumoxane (MAO) for the homopolymerization of norbornene (NB) and 5-ethylidene-2-norbornene (ENB) and for the copolymerization of NB with 5-vinyl-2-norbornene (VNB) or ENB with activities of more than 106 gPNB/(molPd·h). The higher activity of 7/MAO over 4/MAO towards NB homopolymerization was reversed when the olefin-substituted VNB or ENB were added. Then, the more strongly bound PPh3 ligand of 4 (versus AsPh3 of 7) can compete with the olefin functionality of VNB or ENB and assume a directing role for the insertion of the ring double bond. As a consequence 4/MAO shows almost the same activity in NB and ENB homopolymerization.
- Blank, Frederik,Vieth, Jana K.,Ruiz, José,Rodríguez, Venancio,Janiak, Christoph
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p. 473 - 487
(2011/02/28)
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- The use of 1,2-dipiperidinoacetylene for the preparation of monometallic diaminoacetylene and homo- or heterobimetallic diaminodicarbene ruthenium(ii) complexes
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The reaction of the ynediamine 1,2-dipiperidinoacetylene (1) with [(η2-COE)Cr(CO)5], [(THF)W(CO)5] and [RuCl2(η6-cymene)]2 afforded homobimetallic complexes 2a, 2b and 3, in which the diaminoacetylene 1 acts as a bis(aminocarbene) ligand by bridging two complex fragments Cr(CO)5 (in 2a), W(CO)5 (in 2b) and RuCl2(η6- cymene) (in 3). The reaction of 1 with [RuCl2(PPh3) 3] gave trans-[(1)RuCl(PPh3)2]Cl, [4]Cl, in which the alkyne 1 coordinates as a 4-electron donor ligand. The cation 4 represents a rare example of a square-planar Ru(ii) complex with a low-spin ground state (S = 0), and its stability can be ascribed to the strong alkyne-metal π-interaction as confirmed by DFT calculations. Treatment with one or two equivalents of NaBPh4 in acetonitrile gave [4]BPh 4 and the dicationic [(1)Ru(PPh3)2(CH 3CN)2](BPh4)2, [5](BPh 4)2. [4]Cl can be used for the preparation of heterobimetallic Ru-Pd bis(aminocarbene) complexes by reaction with [(MeCN) 2PdCl2], resulting in the formation of bimetallic 6 and tetrametallic 7.
- Petrov, Alex R.,Bannenberg, Thomas,Daniliuc, Constantin G.,Jones, Peter G.,Tamm, Matthias
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p. 10503 - 10512
(2011/12/03)
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- Oxidative addition of Sn-C bonds on palladium(0): Identification of palladium-stannyl species and a facile synthetic route to diphosphinostannylene- palladium complexes
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Methyl-, phenyl-, and n-butyltin trichloride RSnCl3 (R = Me, Ph, nBu) react selectivily with palladium(0)-phosphine precursors through the unprecedented oxidative addition of the Sn-C bond. With [Pd(2-PyPPh2)3] (2-PyPPh2 = 2-pyridyldiphenylphoshine), the reaction cleanly leads to stable cationic dichlorostannylene palladium complexes of the general formula trans-[PdR(SnCl2(2-PyPPh2)2)][X] (X = Cl, R = Me ([5]Cl), R = Ph ([6]Cl), R = nBu ([11]Cl); X = RSnCl4, R = Me ([5][MeSnCl4]), R = Ph ([6][PhSnCl4]), R = nBu ([11][nBuSnCl4])). The SnCl 2(2-PyPPh2)2 fragment, formed by intramolecular coordination of the pyridyl groups to the dichlorostannylene moiety, can be considered as a self-assembled pincer-type ligand with a remarkable ability to suppress β-H elimination in its Pd-alkyl derivatives: [11][ nBuSnCl4], containing a Pd-nBu moiety, was found to be stable up to 70 °C. Oxidative addition of SnCl4 on [Pd(2-PyPPh2)3] resulted in trans-[PdCl(SnCl 2(2-PyPPh2)2)]Cl ([7]Cl) and trans-[PdCl(SnCl3(2-PyPPh2)2)] (8). The molecular structure of 8 was determined by single-crystal X-ray crystallography, indicating that the Sn atom of the trichlorostannyl function has an octahedral coordination geometry. In contrast, oxidative addition of the Sn-C bond of RSnCl3 on [Pd(PPh3)4] resulted in palladium trichlorostannyl complexes that were not stable toward cis-trans isomerization, (partial) elimination of SnCl2 (R = Me, Ph), or β-H elimination (R = nBu). The resulting mixtures of palladium alkyl and palladium hydride species were analyzed by multinuclear NMR, resulting in the identification of novel cis-[PdMe(SnCl3)(PPh3) 2] (cis-4), trans-[PdMe(SnCl3)(PPh3) 2] (trans-4), and cis-[PdH(SnCl3)(PPh3) 2] (cis-10) along with previously observed trans-[PdPh(Cl)(PPh 3)2] (1), trans-[PdMe(Cl)(PPh3)2] (3), trans-[PdH(SnCl3)(PPh3)2] (trans-10), and trans-[PdH(Cl)(PPh3)2] (9).
- Cabon, Yves,Reboule, Irena,Lutz, Martin,Klein Gebbink, Robertus J. M.,Deelman, Berth-Jan
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p. 5904 - 5911
(2011/01/03)
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- PROCESS FOR THE PREPARATION OF UNSYMMETRICALLY SUBSTITUTED BIPHENYL COMPOUNDS
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A process for the preparation of unsymmetrical biaryl compounds of Formula (I) wherein, R is alkyl, R' is cyano, protected or unprotected tetrazole, or Formula (a) wherein, R" is alkyl, aryl, aralkyl or alkoxy, said process comprising, reacting Grignard reagent of Formula (II) wherein, R is alkyl; X is halogen with an aryl halide of Formula (III) wherein, X is halogen; R' is a cyano, protected or unprotected tetrazole, or Formula (a) wherein, R" is alkyl, aryl, aralkyl or alkoxy in a suitable solvent in the presence of a palladium catalyst and a ligand and Lewis acid as a co catalyst.
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Page/Page column 9-11
(2008/12/07)
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- Synthesis, characterization, in vitro cytotoxicity and anti-inflammatory activity of palladium(II) complexes with tertiary phosphines and heterocyclic thiolates: Crystal structure of [PdC28H19N8PS2]
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The new four-coordinated mononuclear palladium(II) complexes 1-9 with chelating heterocyclic thiolates and tertiary phosphines with general formula [Pd(L)nCl(R′R2P)] (L = Pym2SH (pyrimidine-2-thiolate), Pur6SH (purine-6-thiolate), Py2SH (pyridine-2-thiolate), R3P = PPh3, P(o-tolyl)3, PPh2Cl), n = 1, 2) have been synthesized by the direct reaction of [PdCl2(R′R2P)2] with polyfunctional heterocyclic thiolates which display a wide variety of coordinations. These compounds were characterized by elemental analysis, FT-IR and multinuclear (1H, 13C and 31P) NMR. The X-ray diffraction study of non-ionic compound 5 showed that the thiolate acts as unidentate and that the chelating (-N,S) ligand adopts a slightly distorted square planar geometry around the palladium atom. In vitro the anti-inflammatory inhibition of compounds 1-9 was 10-15% greater than that of the standard drug Declofenac. Compounds 1 and 4 showed mostly a moderate to low cytotoxicity against seven human tumor cell lines whereas compound 3 was somewhat more active.
- Shaheen, Farkhanda,Badshah, Amin,Gielen, Marcel,Gieck, Christine,Jamil, Mariyam,de Vos, Dick
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p. 1117 - 1126
(2008/04/13)
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- METAL COMPOUND AND PREPARATION METHOD THEREFOR
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The invention concerns the preparation of a metal chelate, in particular a precious metal β-diketonate or a precious metal phosphine complex MLaXb, where M is a metal atom, L is a ligand, X is an anion which is preferably a halide, HCO3ˉ, NO3ˉ, CO32é or carboxylate, a is a number equal to or less than the coordination number of the metal, b is 0, 1, 2 or 3, comprising reacting an ammine compound of metal M with a complexing compound, which is preferably a phosphine or a diketonate. Metal compounds which can be made by this process are also described.
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Page/Page column 5
(2010/11/26)
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- Studies of reactions of o-xylylene-α,α′-dihalides with palladium complexes and the catalytic synthesis of 3-isochromanone
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Homogeneous catalysis by palladium complexes with phosphorus(III) ligands of the carbonylation of o-xylylene dihalides in the presence of water to form 3-isochromanone has been studied. Triphenylphosphine was found to provide the most effective catalyst, and by-products and intermediates of systems containing this ligand have been investigated. 2-Indanone is one by-product but is unstable to decomposition under catalytic conditions. Excess PPh3 is necessary to prolong activity of the catalyst but is also transformed to bis-phosphonium compound [o-C6H4(CH2PPh3)2]X2 (X = Cl or Br); this quaternization has been investigated and the structure of the bromide salt determined by X-ray diffraction. An unstable oxidative addition product of Pd(PPh3)4 was detected as a probable intermediate and related to the previously reported but catalytically-inactive complex trans-Pd(o-CH2C6H4CH2Cl)Cl(PMe3)2, which has been structurally characterized by X-ray diffraction in this work.
- Jones, Ray V.H.,Lindsell, W. Edward,Paddon-Jones, Greg C.,Palmer, Daniel D.,Preston, Peter N.,Rosair, Georgina M.,Whitton, Alan J.
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p. 2378 - 2385
(2007/10/03)
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- Phenoxide-assisted P-C bond cleavage in PdCl2(PPh 3)2 under very mild conditions
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PdCl2(PPh3)2 reacted with NaOAr (Ar = Ph, p-tolyl) at 0 °C to afford PdCl(Ph)(PPh3)2, instead of PdCl(OAr)(PPh3)2, in 12-16% isolated yields based on Pd. The structure was confirmed by NMR and X-ray crystallography. GC-MS analysis of the reaction solution revealed that OPPh2(OAr), OPPh(OAr) 2, and OP(OAr)3 are formed, while NMR studies indicated that PdCl(Ph)(PPh3)2 is produced when PdCl(OAr)(PPh 3)2 decomposes. The reaction of PdCl2(PPh 3)2 with Bu3Sn(OC6H 4-p-OMe) also gave PdCl(Ph)(PPh3)2 in 8% isolated yield. These results suggest that PdCl(OAr)(PPh3) 2 is highly labile and the aryloxy ligand exchanges with the phenyl groups in triphenylphosphine even under very mild conditions.
- Yasuda, Hiroyuki,Maki, Noriko,Choi, Jun-Chul,Abla, Mahmut,Sakakura, Toshiyasu
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p. 1307 - 1310
(2007/10/03)
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- 3-Dimethylaminopropyl chalcogenolate complexes of palladium(II): Syntheses and characterization, including the crystal structures of [Pd(OAc)(ECH 2CH2CH2NMe2)]2· H2O (E = S, Se) and [PdCl(TeCH2CH2CH 2NMe2)]2
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The reactions of the sodium salts of 3-dimethylamino-1- propylchalcogenolates, prepared by sodium borohydride reduction of (Me 2NCH2CH2CH2E)2 in methanol, with Na2PdCl4 yielded homoleptic [Pd(ECH 2CH2CH2NMe2)2] 6 (1) (E = S (1a); Se (1b); Te (1c)). When treated with [Pd(OAc) 2]3 or Na2PdCl4, compounds 1 readily gave binuclear redistribution products [PdX(ECH2CH 2CH2NMe2)]2 where X = OAc (2) (E = S (2a); Se (2b); or Cl (3)) (E = S (3a); Se (3b); Te (3c)), respectively. The terminal acetate/chloride ligands in 2b/3b can be substituted by other ionic ligands like PhSe-. The complexes were characterized by elemental analysis, UV-Vis, IR and NMR spectroscopy. The structures of 2a, 2b and 3c were established by X-ray crystallography. Each molecule has a dimeric structure in which there are two chalcogenolate bridges from the chelating 3-dimethylamino-1-propylchalcogenolate ligands. On pyrolysis, compound 2b affords Pd17Se15.
- Dey, Sandip,Jain, Vimal K.,Varghese, Babu,Schurr, Thilo,Niemeyer, Mark,Kaim, Wolfgang,Butcher, Ray J.
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p. 1449 - 1457
(2008/10/09)
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- PROCESS FOR THE PREPARATION OF DISUBSTITUTED ACETYLENES BEARING HETEROAROMATIC AND HETEROBICYCLIC GROUPS
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A process for the preparation of a disubstituted acetylene bearing heteroaromatic and heterobicyclic groups of formula I is provided wherein X is S, O, or NR1 wherein R1 is hydrogen or a C1-C6 straight or branched alkyl group; R is hydrogen or a C1-C6 straight or branched alkyl group; A is a substituted or unsubstituted pyridinyl, thienyl, furyl, pyridazinyl, pyrimidinyl or pyrazinyl group; n is 0--4; and B is H2 -COOH, -CH2OH, -CHO or a C1-C6 alkyl acetal derivative, -COR2or a C1-C6 alkyl ketal derivative where R2 is -(CH2),,,CH3 where m is 0-4 or COOR3 wherein R3 is a straight or branched C1-C30 alkyl group, a substituted or unsubstituted C6-C30 aromatic group, a substituted or unsubstituted C3-C30 cycloalkyl, a substituted or unsubstituted C3-C30 cycloalkylalkyl, a substituted or unsubstituted C3-C30 cycloalkenyl, a substituted or unsubstituted C5-C30 aryl, a substituted or unsubstituted C5-C30 arylalkyl, a substituted or unsubstituted C5-C30heteroaryl, a substituted or unsubstituted C3-C30 heterocyclic ring, a substituted or unsubstituted C4-C30 heterocyclylalkyl, a substituted or unsubstituted C6-C30 heteroarylalkyl, the process comprising a Sonogashira coupling reaction between a compound of formula II wherein X and R have the aforestated meanings, with a compound of formula III wherein X' is a halogen and A, n and B have the aforestated meanings, in the presence of a base and a transition metal catalyst and in a polar aprotic solvent.
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Page/Page column 12
(2010/02/15)
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- Reactivity of [Pd{CH2C(O)Me}Cl]Mn toward isocyanides
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The capacity of [Pd{CH2C(O)Me}Cl]n to prepare chloro-monoacetonyl or monoacetonyl palladium (II) complexes was analyzed. The established synthetic procedures for these complexes invariably involve the presence of other strongly coordinated ligands. The thermal transformation of these compounds into C-palladated β-ketoenamine complexes resulting from insertion of one molecule of the isocyanide followed by a β-ketoimine to β-ketoenamine tautomerization processes. The resulting complexes were the first palladium compounds containing such ligands acting as a chelate.
- Vicente, Jose,Areas, Aurelia,Fernandez-Hernandez, Jesus M.,Bautista, Delia,Jones, Peter G.
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p. 2516 - 2527
(2008/10/09)
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- Synthesis of novel metal-germavinylidene complexes from bisgermavinylidene
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The bisgermavinylidene [(Me3SiN=PPh2) 2C=Ge→Ge=C(PPh2=NSiMe3)2] (1) has been used as the source of unstable germavinylidene for the synthesis of a series of metal-germavinylidene complexes. Treatment of 1 with M(PPh 3)4 (M = Ni, Pd) afforded the metal-germavinylidene complexes [{(Me3SiN=PPh2)2C=Ge} 2Ni(PPh3)2] (2) and [{(Me3SiN= PPh2)2C= Ge-μ2}Pd(PPh3)] 2 (3), respectively. The germavinylidene moiety from 1 acts as a two-electron terminal and bridging ligand, respectively. Similar reaction of 1 with AgCl or Aul gave [(Me3-SiN=PPh2)2C=Ge(Ag) (Cl)]2 (5) and [(Me3SiN=PPh2) 2C=Ge(Au)(I)]2 (6), respectively. The result has shown that the germavinylidene moiety from 1 behaves as a Lewis base and undergoes an insertion reaction into the metal-halogen bond. X-ray structures of 2, 3, 5, and 6 have been determined.
- Leung, Wing-Por,So, Cheuk-Wai,Kan, Kwok-Wai,Chan, Hoi-Shan,Mak, Thomas C. W.
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p. 5033 - 5037
(2008/10/09)
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- The electron-poor phosphines P{C6H3(CF 3)2-3,5}3 and P(C6F 5)3 do not mimic phosphites as ligands for hydroformylation. A comparison of the coordination chemistry of P{C 6H3(CF3)2-3,5}3 and P(C6F5)3
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The fluoroaryl phosphines P{C6H3(CF3) 2-3,5}3 (La) and P(C6F 5)3 (Lb) form the complexes trans-[MCl 2(La)2] and trans-[MCl2(L b)2] (M = Pd or Pt) which have been isolated and fully characterised. 31P NMR studies of competition experiments show that the stability of trans-[PdCl2L2] is in the order L = Lb a 3. The crystal structure of trans-[PtCl2(La)2] is reported and reveals that the Pt-P bond lengths in trans-[PtCl2L2] are in the order L = Lb a 3. The equilibria established when [Pt(norbornene)3] is treated with La or Lb are investigated by 31P and 195Pt NMR spectroscopy and the species [PtLn(norbornene)3-n] (n = 1-3) identified. Ligands La and Lb appear to have similar affinities for platinum(0). The complexes trans-[MCl(CO)(La) 2] and trans-[MCl(CO)(Lb)2] (M = Rh or Ir) have been synthesised and fully characterised; the values of vco are comparable with those for analogous phosphite complexes. The ligands L a, Lb, P(C6H2F 3-3,4,5)3 (Lc), P{C6H 4(CF3)-2}3 (Ld), PPh3 and P(OPh)3 have been tested in rhodium-catalysed hydroformylation of 1-hexene and La, Lb, and PPh3 have been tested in rhodium-catalysed hydroformylation of 4-methoxystyrene. Ligands L a, and Lb, have been shown to be stable under the hydroformylation catalysis conditions. For the 1-hexene reaction, the activity and selectivity for La and Lc are very similar to the PPh3 catalyst (TOF ca. 400 h-1; n: iso 2.5-3.0) but for the sterically demanding Lb and Ld the activity and selectivity was much lower than with PPh3 (TOF ca. 15, n: iso ratio 0.6). Thus, the yield of heptanals obtained with the catalyst derived from La is 94% while under the same conditions with Lb only 6%. The TOF for the La/Rh catalyst was 5 times lower than for the P(OPh)3/Rh catalyst despite the superficially similar ligand electronic characteristics for La and P(OPh)3. The Royal Society of Chemistry 2005.
- Clarke, Matthew L.,Ellis, Dianne,Mason, Kate L.,Orpen, A. Guy,Pringle, Paul G.,Wingad, Richard L.,Zaher, Damien A.,Baker, R. Tom
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p. 1294 - 1300
(2007/10/03)
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