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A critical query on literature is the approach used to immobilize homogeneous catalysts to improve their efficiency and recyclability. This work aims to compare the immobilization level of a kind of Pd‐N,N′‐bis(salicylidene)‐o‐phenylenediamine complex on high surfaces of polymeric resins to provide heterogenous catalysts for Mizorocki‐Heck reaction. The preparation method involves two strategies: (i) polymerization of the ligand before the complex‐synthesis in a "multi‐step (MS)" approach and (ii) a direct "one‐step" (OS) immobilization by polymerization of the metal‐containing monomers (MCMs) as co‐monomer. Both approaches effectively yield polymers with a larger surface area, over 700 m2 g−1, and suitable thermic properties to use in the proposed reaction. In addition, the characterization of the polymers by XRD, XPS, and TEM demonstrates notable differences in Pd species on polymer support associated with the methodological approach to immobilizing the metal complex. [ABSTRACT FROM AUTHOR]

Homopolymerization of styrenic monomer featuring different functional group and their copolymerization with carbon monoxide were investigated by imine-pyridine palladium complex with the assistance of AgSbF 6. Poly(4-vinylbenzyl chloride) and poly(4-N,N-dimethylaminostyrene) were produced probably according to coordination-insertion mechanism. In the presence of carbon monoxide, substituted styrenes except for the 4-N,N-dimethylaminostyrene were copolymerized with CO to yield polyketones by the same catalysts. Thus, polyketones featuring chloromethyl group, diphenylaminomethyl group and quaternary ammonium salt were produced for the first time by direct alternating copolymerization. DSC results disclosed that glass transition temperature of the resulting polyketones was significantly affected by the substituents. The T g of polyketone featuring quaternary ammonium salt was 160 °C. [Display omitted] • Homopolymerization of 4-vinylbenzyl chloride or 4-N,N-dimethylaminostyrene catalyzed by imine-pyridine palladium catalyst according to coordination-insertion mechanism for the first time. • Alternating copolymerization of a series of substituted styrenes with carbon monoxide by palladium catalyst to yield polyketones featuring different functional groups. • High glass transition of polyketones featuring quaternary ammonium salt produced by direct copolymerization. [ABSTRACT FROM AUTHOR]

Sterically hindered 2‐iminopyridine derivatives and their palladium chlorides complexes are designed and prepared, which efficiently promote the Suzuki–Miyaura coupling (SMC) reaction in aqueous solution. Besides the good to excellent yields and broad substrate scope, these catalysts can be reused for at least four new batches of the substrates. Spontaneous separation of coupling products in the aqueous reaction medium is the additional striking feature of this catalytic process. Furthermore, catalytic performance of palladium complexes bearing the azo‐bridged phenyl groups was greatly influenced by the UV irradiation due to the cis/trans photoisomerization of azo unit of the catalysts. In conclusion, titled palladium complexes provide a green, sustainable, cost‐effective, and convenient process to synthesize SMC products at multi‐gram‐scale reaction. [ABSTRACT FROM AUTHOR]

Palladium catalysts modified with iminopyridine ligands were employed for ethylene/CO and styrene/CO copolymerization and ethylene/styrene/CO terpolymerization. Our studies revealed that the steric and electronic effects of the catalysts play key, yet distinct roles in these polymerization reactions. The thermal properties of the polyketones were engineered by varying the styrene content in terpolymers derived from ethylene, styrene, and CO sources, with increased styrene ratios yielding reduced polyketone crystallinity. [ABSTRACT FROM AUTHOR]

This study deals about preparation of palladium(II) complex of 3,5– bis (2–benzothiazolyl)pyridine supported on nano silica functionalized with trimethoxysilylpropyl chloride, Pd(II)Cl 2 –BTP@TMSP–nSiO 2 . The synthesized heterogeneous catalyst was characterized by FT–IR, UV–Vis spectroscopies, field emission scanning electron microscopy, energy dispersive X–ray analysis, transmission electron microscopy and elemental analysis. Furthermore, the Pd(II)Cl 2 –BTP@TMSP–nSiO 2 was found as a highly efficient catalyst in the Sonogashira cross–coupling of aryl halides (iodides, bromides and chlorides) with phenyl acetylene. This heterogeneous catalyst was easily recyclable and reused several times without significant loss of reactivity. Finally, its catalytic activity was compared with homogeneous catalyst to demonstrate the effect of supporting on the catalytic activity. [ABSTRACT FROM AUTHOR]

A series of bulky amine palladium complexes {[(Ar-NH 2 ) 2 PdCl 2 ]} were synthesized and characterized. The catalytic activity of the palladium complexes was evaluated via the direct C–H arylation of thiazoles with aryl bromides in aerobic conditions at 80–100 °C. Under the optimal conditions, 0.5–0.05 mol% of the bulky palladium complexes were found to be very efficient and produced the desired cross-coupling products in high yields. [ABSTRACT FROM AUTHOR]

A new palladium(II) complex containing two sterically hindered ligands, a P,P-bonded diphosphine and N,N-bonded Schiff base, within the same coordination sphere has been synthesized and investigated as a catalyst for the Suzuki-Miyaura crosscoupling reactions of aryl halides with arylboronic acids. The reaction was highly efficient with aryl bromides in water at room temperature and aryl chlorides in dimethylformamide under relativelymild conditions. Excellent yields of coupling productswere obtained for a wide range of aryl halides including heteroaryl halides with a low loading of catalyst. [ABSTRACT FROM AUTHOR]

The Heck reactions of various aryl halides with olefins using {[PhPCHPPhCH = C(O)(CH)] PdCl} as efficient catalyst has been investigated. The mononuclear palladacycle complex showed excellent activity in aqueous phase including the C(sp )-C(sp ) cross coupling reactions. The advantages of the protocol are high yields, short reaction time, a cleaner reaction profile and notable simplicity. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In the present work, silica-coated magnetic nanoparticles [Fe 3 O 4 @SiO 2 @C22–Pd(II)] were prepared and characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometer, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, elemental analysis, inductively coupled plasma, thermogravimetric and differential thermal analysis. This heterogeneous catalyst is utilized as an effective catalyst for the Suzuki–Miyaura coupling of arylboronic acids and aryl halides, and the cross-coupling reaction of aryl halides and thiols. The catalyst was easily separated by magnetic decantation and the recovered catalyst was reused for five cycles without any significant loss of the catalytic activity. [ABSTRACT FROM AUTHOR]

Glycine, as a kind of commercially available and inexpensive ligand, is used to prepare an air-stable and water-soluble catalyst used in Sonogashira reaction in our study. In the presence of 1% [PdCl2(NH2CH2COOH)2] as catalyst, excellent catalytic activity towards the Sonogashira coupling of aryl iodides with terminal alkynes without using any additive such as Cu(I)-cocatalyst is observed in a mixture of water and acetone (3/3 mL) under air at 60 °C with NaOH as a base, giving products in good to excellent yields. [ABSTRACT FROM AUTHOR]

Eight novel palladium N-heterocyclic carbene (Pd-NHC) complexes were synthesized by the reaction of chloro 1,3-dialkylbenzimidazolin-2-ylidene silver(I) complexes with bis(benzonitrile)palladium(II) chloride in dichloromethane. These eight Pd-NHC complexes are as follows: bis[1-phenyl-3-(2,4,6-trimethylbenzyl)benzimidazol-2-ylidene]dichloropalladium(II), bis[1-phenyl-3-(2,3,5,6-tetramethylbenzyl)benzimidazol-2-ylidene]dichloropalladium(II), bis[1-phenyl-3-(2,3,4,5,6-pentamethylbenzyl)benzimidazol-2-ylidene]dichloropalladium(II), bis[1-phenyl-3-(3,4,5-trimethoxybenzyl)benzimidazol-2-ylidene]dichloropalladium(II), bis[1-(2-diethylaminoethyl)-3-(3-methylbenzyl)benzimidazol-2-ylidene]dichloropalladium(II), bis[1-(2-diethylaminoethyl)-3-(2,3,5,6-tetramethylbenzyl)benzimidazol-2-ylidene]dichloropalladium(II), bis[1-(2-morpholinoethyl)-3-naphthalenomethylbenzimidazol-2-ylidene]dichloropalladium(II) and bis[1-(2-morpholinoethyl)-3-(2-methylbenzyl)benzimidazol-2-ylidene]dichloropalladium(II). Also, these synthesized complexes were fully characterized using Fourier transform infrared, 1H NMR and 13C NMR spectroscopic methods and elemental analysis techniques. These synthesized novel Pd-NHC complexes were tested as catalysts in the direct of 2- n-butylthiophene, 2- n-butylfuran and 2-isopropylthiazole with various aryl bromides at 130°C for 1 h. The complexes showed very good catalytic activities in these reactions. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Asymmetric cycloaddition reaction between 3,4-dimethyl-1-phenylarsole and ethyl vinyl ketone was promoted by the palladium complex containing ortho-metalated (S)-[1-(dimethylamino)ethyl]naphthalene as the chiral auxiliary. The keto group in the resulting arsanorbornene cycloadducts could be located stereospecifically in the endo or exo position by controlling the electronic properties of the organopalladium promoter. In the intermolecular cycloaddition reaction, a pair of separable diastereomeric palladium complexes was obtained in the ratio of 2:1. In the intramolecular process, however, only one As–O bidentate arsanorbornene palladium complex was produced stereoselectively. The arsenic-elimination reaction was readily observed on the corresponding endo- and exo-ketoarsine ligands. The absolute configuration and the coordination property of the enantiomerically pure endo-cycloadduct had been established by single-crystal X-ray analysis. [Copyright &y& Elsevier]

Highlights: [•] PdCl2(phen)@Y exhibits high aminocarbonylation activity for synthesis of amides. [•] PdCl2(phen)@Y is re-used up to 16 times without any loss of activity in reaction. [•] Double protection for the active Pd complex accounts for excellent recyclability. [ABSTRACT FROM AUTHOR]

Three complexes with same components, PdII, 2-sulfobenzoate and 1,10-phenanthroline, [Pd(phen)2]⋅2(2-Hsb) (1), [Pd(phen)2](2-Hsb)⋅(2-Hsb)⋅2H2O (2), and [Pd(phen)2]⋅[Pd(phen)(2-sb)2]⋅6H2O (3), where 2-H2sb is 2-sulfobenzoic acid and phen is 1,10-phenanthroline, were synthesized and characterized by IR spectra, elemental analyses, thermogravimetric analyses, UV–vis absorption spectra and powder X-ray analysis. Single X-ray crystal structural analyses showed that1and2are ionic species, while3is a dimer through weak bonding interactions. In1and2, 2-Hsb−ligands are partly deprotonated and it is fully deprotonated in3. In2and3there are hydrogen bonds andπ–πinteractions. Extended hydrogen bonding structures for2and3are 1-D and 3-D architectures, respectively. The oxidation of methyl phenyl sulfide by1-3as homogeneous catalysts gave high conversion and selectivity in methanol. The addition of 2-sulfobenzoic acid in the catalytic reaction further promotes the conversion. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sonogashira coupling using [PdCl(E∩NMe2)] n complexes catalyst. [•] Dimeric and trimeric Pd(II) complexes of hemi-labile chalcogenolate ligands. [•] Sonogashira cross-coupling reaction in the absence of copper and phosphine ligand. [•] Dimeric complexes show better activity than mono and trimeric complexes. [•] Selenium containing dimeric complex shows better activity than sulfur counterpart. [ABSTRACT FROM AUTHOR]

Abstract: A new palladium complex derived from a bidentate Schiff-base ligand showed excellent activity as catalyst for the Suzuki–Miyaura cross-coupling reactions of less reactive aryl chlorides with arylboronic acids. Under an optimized condition, moderate-to-excellent yields of biaryls were obtained with a wide range of substrates at a relatively low loading of catalyst (0.2mol%). [Copyright &y& Elsevier]

Abstract: Herein we provide an overview on the unique properties of the sterically demanding IBiox-[(−)-menthyl]∙HOTf ligand (such as flexibility and sterics) and an application of this ligand in Pd-catalyzed asymmetric intra- and intermolecular α-arylation reactions. Furthermore we demonstrate the synthesis of novel NHC–metal complexes and a new bifunctional NHC ligand whilst insight into the mechanistic mode of action of IBiox-[(−)-menthyl]∙HOTf in catalysis is provided. [Copyright &y& Elsevier]

Abstract: A well-defined N-heterocyclic carbene (NHC)–palladium chloride–imidazole complex exhibited high catalytic activity in the coupling reaction of arylboronic acids with carboxylic acid anhydrides in pure water under mild conditions. Under the optimal conditions, all reactions gave the desired coupling products in moderate to high yields. [Copyright &y& Elsevier]

Abstract: A novel 1-glycyl-3-methyl imidazolium chloride–palladium (II) complex [[Gmim]Cl–Pd (II)] was found to be a heterogeneous catalyst for an efficient Heck reaction with good to excellent yield under solvent free condition. Tetra-coordinated palladium complex was prepared by reacting PdCl2 with 1-glycyl-3-methyl imidazolium chloride and its catalytic function invented for the Crmation. Spectroscopic evidence of complex has been proved by powder XRD, SEM, FT-IR and AFM. This protocol provides a simple strategy for the generation of a variety of new Cnder environmentally benign condition. [Copyright &y& Elsevier]

Abstract: Asymmetric hydrogenation of tetrasubstituted olefins of cyclic β-(arylsulfonamido)acrylates produces the corresponding cyclic β-(arylsulfonamido)propionates using Pd(OCOCF3)2/diphosphine complexes as catalysts in the presence of TFA with up to 96% ee. [Copyright &y& Elsevier]

Abstract: Two new bis(diphenylphosphino)amines, N,N-bis(diphenylphosphino)benzidine 1 and N,N-bis(diphenylphosphino)-3,3-dimethoxybenzidine 2 were prepared by aminolysis. Their corresponding oxides, sulfides and selenides were readily prepared by reaction with hydrogen peroxide, elemental sulfur or grey selenium, respectively. Symmetric dinuclear palladium and platinum complexes were also isolated from the reaction with [M(cod)Cl2] (M=Pd or Pt, cod=cycloocta-1,5-diene). All compounds were characterized by IR and NMR spectroscopy and elemental analysis and the structure of [(Ph2P)2N–C6H4–C6H4–N(PPh2)2] was determined by single crystal X-ray diffraction. The catalytic activity of palladium complexes in Suzuki coupling reactions was also investigated. [Copyright &y& Elsevier]

Abstract: Two new pentamethylene-bridged bis-imidazolium dication ligands (L1 =1,5-bis(1-(4-cyanophenyl)-imidazolium-1-yl)pentane dibromide) and L2 =1,5-bis(1-(4-methoxyphenyl)-imidazolium-1-yl)pentane dibromide) bearing CPI (1-(4-cyanophenyl)-imidazole) and MPI (1-(4-methoxyphenyl)-1H-imidazole)-functionality have been prepared via the reaction of 1,5-dibromopentane with a substituted imidazole derivative. The imidazolium ligand L1 and L2 on reaction with [PdBr2(C6H5CN)2] led to the formation of neutral bis-imidazolium dication palladium(II) complexes [L1] [PdBr4] [1] (L1 =1,5-bis(1-(4-cyanophenylimidazolium-1-yl)pentane) and [L2] [PdBr4] [2] (L2 =1,5-bis(1-(4-methoxyphenyl) imidazolium-1-yl)pentane), respectively. The new ligands as well as their palladium(II) complexes, has been characterized by elemental analysis, electronic, IR, 1H and 13C NMR, FAB–MS and ESI–MS spectroscopy. The molecular structure of the representative complex [L2] [PdBr4] [2] have been determined by single crystal X-ray analysis. Complex 2 exhibits the strong intra- and inter-molecular C–H···X (X=Br, O, π) weak interactions, which plays an important role in stabilizing the crystal packing. Furthermore, the C–H···O interactions in 2 lead to a single-helical motif. The complexes 1 and 2 exhibited good activity in a model Suzuki–Miyaura coupling reaction. [Copyright &y& Elsevier]

Abstract: N-Heterocyclic carbene–Pd(II) complex 1 derived from proline was found to be an efficient catalyst in the Mizoroki–Heck reaction of aryl bromides and iodides performed in water. The reactions can tolerate various functional groups in the substrates and all gave the corresponding coupling products in good to high yields. [Copyright &y& Elsevier]

Abstract: A new type of well-defined N-heterocyclic carbene (NHC)-palladium chloride-imidazole complexes derived from IPr HCl or IMes HCl, PdCl2 and 1-methylimidazole exhibits high catalytic activity in the room-temperature Suzuki-Miyaura coupling reactions of aryl or heteroaryl chlorides. Moreover, the large-scale (20.0 mmol) couplings in the presence of 0.01 mol% catalyst loading can also give the corresponding coupling products in high yields. [Copyright &y& Elsevier]

Abstract: A new class of well-defined NHC–Pd(II)–Im complexes was synthesized and was found to be an efficient catalyst for the amination reactions of aryl chlorides. Under the optimal reaction conditions, a range of amines can be coupled to give the amination products in good to high yields. [Copyright &y& Elsevier]

Abstract: Combination of 3,5-dimethyl-1-(2-(diphenylphosphino)phenyl)-1H-pyrazole, A, and 3-tert-butyl-5-methyl-1-(2-(diphenylphosphino)phenyl)-1H-pyrazole, B, with Pd2(dba)3 furnished excellent catalysts for Stille, Kumada and Hiyama cross-coupling reactions. Effects of solvents, bases and ligand/palladium ratio on efficiency of coupling reactions were studied. Molecular structures of palladium(II) complexes of A and B determined by single-crystal X-ray diffraction method revealed a close similarity of ligand arrangement around the metal centre. [Copyright &y& Elsevier]

A reusable, air-stable polymer-anchored palladium (II) Schiff base complex catalyst, P-[{(NCH)C6H4}Pd(OAc)]2 was prepared and was found to be highly active in Suzuki cross-coupling reactions of aryl halides with phenyl boronic acid in an aqueous medium to give biaryl products in high yields. [ABSTRACT FROM AUTHOR]

Abstract: Several new ortho-alkyl and heteroalkyl substituted aryl and aryl alkyl phosphanes and their palladium complexes have been selectively prepared, characterized and compared as potential catalysts for the Suzuki coupling reaction. The modification of the structures of the palladium complexes were made in search of the best possible catalytic activity. The novel catalysts were subsequently used to synthesize sterically hindered bi- and triaryls by coupling various bulky, unactivated bromoxylenes and chloroxylenes with a range of phenyl boronic acids under microwave irradiation. We showed that under optimized reaction conditions, very good results can be obtained with a selection of the new phosphanes and their mononuclear palladium complexes. [Copyright &y& Elsevier]

Abstract: N,N,O-Tridentate ligands 1–9 were prepared from the condensation of amines with nine aromatic aldehydes or ketones. These ligands are thermally stable and neither air- nor moisture-sensitive. Combination of either 2-methoxy-6-[(pyridine-2-ylmethylimino)-methyl]-phenol, 1 or 2-(benzothiazol-2-yl-hydrazonomethyl)-4,6-di-tert-butyl-phenol, 6 with Pd(OAc)2 furnished an excellent catalyst precursor for the Suzuki–Miyaura cross-coupling of various aryl bromides with arylboronic acids. The effects of varying solvents, bases, and ligand/palladium ratios on the performance of the coupling reaction were investigated. The molecular structures of both free ligand 1 and its palladium acetate complex 10 were determined by single-crystal X-ray diffraction methods. The DFT studies revealed that the catalytic performance of palladium complexes involving this type of a ligand may differ greatly upon a small variation in its structure. [Copyright &y& Elsevier]

• Synthesis of magnetic chitosan-supported palladium complex is presented. • Suzuki-Miyaura reactions are performed using Fe 3 O 4 CS@tet-Pd(II) catalyst. • The catalyst can be recycled for multiple reactions with almost no loss in activity. • Easy separation of catalyst and good yields of products. • The catalyst offers a promising avenue for magnetic materials in organic synthesis. The utilization of various tetrazoles as efficient ligands is a promising method for the functionalization of tetrazole-based heterogeneous catalysts. Their combination with magnetic species and natural supports exposes huge opportunities for the practical applications of heterogeneous catalysts. In this study, a green and novel strategy is applied to synthesize Fe 3 O 4 magnetic nanoparticles (MNPs) incorporated with chitosan (CS) and 5-amino-1 H -tetrazole with a long tail ((3-chloropropyl)trimethoxysilane) to immobilize palladium catalyst designated as Fe 3 O 4 CS@tet-Pd(II). The prepared Fe 3 O 4 CS@tet-Pd(II) was used as an efficient and magnetically recyclable catalyst for the Suzuki-Miyaura cross-coupling reaction (SMCR) using a mixture of EtOH/H 2 O as green media under aerobic conditions. All the expected products were obtained in high yields, indicating the high efficiency of this catalyst for the preparation of various biaryls by SMCR. Various latest techniques were used to characterize Fe 3 O 4 CS@tet-Pd(II), e.g. , Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS) elemental mapping, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning TEM (STEM), high resolution TEM (HR-TEM), vibrating sample magnetometer (VSM), fast Fourier transform (FFT), thermogravimetric analysis (TGA), etc. This study presents a unique example of 5-amino-1 H -tetrazole grafted on Fe 3 O 4 CS, which can easily be separated using an external magnet and reused five times without significant decrease of catalytic activity. In addition, the introduced method has significant advantages such as the utilization of natural and inexpensive materials, easy work-up, high yields of products, and high catalytic activity. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: A bulky, inexpensive and simple bidentate ligand 1,4-bis(2-hydroxy-3,5-di-tert-butylbenzyl)piperazine (1) has been synthesized and characterized. The palladium catalyst was formed by combination of 1 with [Cl2Pd(COD)] in a ratio of 1:1, tested in the Suzuki–Miyaura and Mizoroki–Heck cross-coupling reactions. Coupling of a variety of aryl bromides with phenylboronic acid using methanol as solvent at room temperature, or at 60°C, gave generally high yields of coupled products. Coupling of aryl chlorides with organoboron reagent at 110°C in DMF afforded good yields of biaryls under aerobic conditions. This non-phosphorus, air and moisture stable catalyst also displays good activity for Mizoroki–Heck coupling reaction in methanol at 60°C with various aryl chlorides and bromides. [Copyright &y& Elsevier]

Abstract: A well-defined NHC–Pd(II)–Im complex was proved to be an efficient catalyst for the Hiyama reaction of a variety of aryl chlorides with aryltrimethoxysilanes. Under the optimal conditions, all reactions took place smoothly to give the corresponding coupling products in moderate to high yields. [Copyright &y& Elsevier]

Abstract: The palladium-catalyzed Heck reaction was effected with two ruthenium complexes bearing unique heterocyclic 1,2,4-diazaphospholide ligands that contain sp2-hybridized phosphorus atoms. [Copyright &y& Elsevier]

The development of recoverable catalysts based on the combination of synthetically demanding ligands with transition metals attracts a lot of attention, especially from the environmental point of view. In this paper, we describe the preparation of a recoverable polystyrene supported chiral palladium catalyst based on PyOx ligand suitable for asymmetric 1,4-addition of arylboronic acids to cyclic 3-substituted five- and six-membered enones. In the reaction, all‑carbon quaternary stereocenters are formed with a high level of enantioselectivity (up to 91% ee) and conversion (up to 99%). The catalyst was used in 6 cycles with no loss of enantioselectivity and only a small decrease in conversion. A solution of the problems associated with the transition from homogeneous to heterogeneous catalytic systems is discussed. Unlabelled Image • Recoverable polystyrene supported chiral palladium catalyst based on PyOx ligand was prepared. • The catalyst was used for asymmetric 1,4-addition of arylboronic acids to cyclic 3-substituted five- and six-membered enones. • All-carbon quaternary stereocenters are formed with a high level of enantioselectivity and conversion. • The catalyst was used in 6 cycles with no loss of enantioselectivity and only a small decrease in conversion. [ABSTRACT FROM AUTHOR]